ויאמר משה אל האלקים הנה אנכי בא אל בני ישראל ואמרתי להם אלקי אבותיכם שלחני אליכם ואמרו לי מה שמו מה אמר אליהם. ויאמר אלקים אהי' אשר אהי' ויאמר אלקים אל משה כה תאמר לבני ישראל אהי' שלחני אליכם
Moshe said to G-d, “Behold, when I come to Bnei Yisrael and say to them, ‘The G-d of your forefathers has sent me to you,’ and they say to me, ‘What is His Name?’ what shall I say to them?” Hashem answered Moshe, “I Shall Be As I Shall Be.” And He said, “So shall you say to Bnei Yisrael, ‘I Shall Be has sent me to you.’”
Our Sages teach us that G-d has many names, each one alluding to a different attribute with which He operates in His world. Some names denote His attribute of judgment; some, His attribute of mercy; some valor and might; some loving kindness and compassion. However, the secret of this name אהי', I Shall Be, which is only found here in Scripture, is not explained by our Sages. The Rishonim are the first ones to shed light on the secret of this name. Firstly, there is debate as to whether this name is indeed one of G-d’s Holy Names and therefore impermissible to erase. There are two versions in the wording of the Rambam, as brought down by the Kessef Mishna, as to whether this name is included in G-d’s inerasable Names. The first version omits this name when listing G-d’s inerasable Names whereas the second version includes it. In our version of the Gemara, as mentioned in the Kessef Mishna, the name אהי' אשר אהי' is listed as a Name. This version seems to indicate that אהי' on its own is not a Name, rather the three words אהי' אשר אהי' combined constitute a Name. This is evidenced by the Targum not translating the word אשר into Aramaic"די")), rather leaving the word אשר in Hebrew, as he does elsewhere with G-d’s Names, thus demonstrating that the three words together form a Name of G-d.
Rashi explains this Name, אהי' אשר אהי', as follows: אהי' עמם בצרה זו, I Shall Be with them during this trouble [Egypt], אשר אהי' עמם בשעבוד שאר מלכויות, as I Shall Be with them in other exiles. Rashi goes on to say how upon hearing this, Moshe asked G-d why the Jews should be told of other exiles—the present one is more than enough—to which G-d responded that Moshe should tell Bnei Yisrael only "אהי' שלחני אליכם" I Shall Be has sent me to you, and not אהי' אשר אהי', I Shall Be as I Shall Be, which would allude to other exiles. This seems to indicate that indeed G-d agreed with Moshe, and therefore the name אהי' אשר אהי', I Shall Be as I Shall Be, was not given to Bnei Yisrael. This would seem to indicate furthermore that only אהי' is a Name but אהי' אשר אהי' is not a Name, though it’s more probable that according to Rashi, neither are names of G-d, but rather a phrase that has a simple and clear meaning: that G-d will be with us.
The Ramban offers numerous ways of understanding this passuk. One of them is that G-d rejected Moshe’s request that He reveal a Name for him to tell Bnei Yisrael, and instead G-d answered him
“Why should they [Bnei Yisrael] ask for My Name? They need no other proof, other than that I will be with them in all their afflictions. They need only call out to Me and I will answer them.” This is the greatest proof that there is a G-d in Israel, who is close to us whenever we call out to Him and that there is a G-d who judges in the land.
According to the above explanation, it would seem that אהי' is not an inerasable Name.
The Ramban writes furthermore that “ אהי' אשר אהי'means as you are toward Me so will I be toward you. If they [Bnei Yisrael] open their hands and give charity, I too will open My hand [and deal kindly with them].” This explanation, too, warrants a closer examination as to whether this is a Name of G-d or perhaps it isn’t and this is simply a lesson for us that G-d acts with us measure for measure.
The Ramban adds,
Rav Saadia Gaon wrote regarding the meaning of אהי' אשר אהי' that its explanation is the One Who has never ceased to be nor will He ever cease to be, for He is first and He is last, i.e, He is eternal. The Rambam writes in Moreh Nevuchim that the meaning of אהי' אשר אהי' is “the Being that exists, Whose existence is a necessity. The proof which Moshe was to give to Bnei Yisrael consisted of demonstrating that there is a Being of absolute existence, Who has never not existed and Who will never not exist.”
According to this understanding, the name אהי' אשר אהי' is indeed a Holy Name whose meaning is eternity—I am first and I am last. Thus we have three ways of understanding the essence of this name אהי' אשר אהי'.
The Rashbam offers a profound explanation of this Name: The passuk states זה שמי לעלם וזה זכרי לדר ודר. The Rashbam explains that זה שמי לעלם, this is My Name forever, is referring to אהי', I Shall Be, mentioned in the previous passuk, and זה זכרי לדר דר, this is My remembrance from generation to generation is referring to the name הוי', Hashem, mentioned in this passuk. Just like we do not call kings by their given names rather by a title suggestive of their stature (your highness, your majesty, etc.), so too, says the Rashbam, do we call Hashem not by his Name but rather by a different moniker. G-d calls Himself אהי' , and we call him יהי', or הוי' (aו' coming in place of a י').
What the Rashbam means is that the name אהי' is the same as the more common Name הוי'. This explains why we do not find this name anywhere else in Scripture aside from here; only here was G-d requested to utter His Name and reveal it to a human being, and therefore He said אהי' אשר אהי'. But in every other place, where we are the ones uttering G-d’s Name, it is written as הוי'. The Rashbam teaches us that the nameאהי' is the same as הוי', the Name of G-d’s attribute of mercy, telling us that the key to redemption is through the Name of G-d indicative of mercy. This is why G-d tells Moshe “So shall you say to the Children of Israel, ‘I Shall Be has sent me to you,’” to inform Bnei Yisrael in the midst of their dark exile, that they will not suffer under Egyptian tyranny forever. The redemption will not take long; they will be redeemed by אהי'.
Said G-d, I am with you in anguish, as this burden of building storage cities for Pharaoh is forced upon you; I am with you through the hardships of this slavery and your weariness of sorrow. This hardship will not endure forever, for your salvation is close to coming. This exile in Egypt serves as a refining process, like precious metal in an iron furnace. I have remembered you and all that has been perpetrated against you. Listen! Says Moshe to Bnei Yisrael, אהי' has sent me to you to redeem you, with loving kindness and mercy. Hence, “and the people believed, and they heard that Hashem had remembered the Children of Israel and that He saw their affliction, and they bowed their heads and prostrated themselves.”
This is what stood and still stands true for Bnei Yisrael through the darkness of their exile. The Jewish people have been sent into exile time and again and we still suffer in exile. Bnei Yisrael have been and still are a byword of mockery in the eyes of the nations. Yet a Jew stands strong in his belief as he awaits faithfully the future redemption. He davens morning, noon and evening that his eyes may witness the Divine Presence return to Zion in mercy. The Jew knows that his exile is not for naught. As our Sages say " "צדיקים אין להם מנוחה בעולם הזה The righteous have no rest in this world. There is reason and purpose for our long exile. G-d was with us in our other exiles and so too is He with us in this one. אהי' אשר אהי'—he redeemed us then and will redeem us in future. Every Jews knows this intuitively and lives his life accordingly, with the knowledge that this world is merely an entryway to the World to Come and toward that goal he aspires.
Rashi says אהיה עמכם בגלות זו ואהיה עמכם בגלות אחרת, I shall be with you in this exile and I shall be with you in the other exile. The heralding of the redemption will uplift Bnei Yisrael and refocus their outlook from the present to the future, to know and believe that their salvation will come even if it tarries, and then will the words of the Novi Yeshaya be fulfilled: "אז יבקע כשחר אורך וארוכתך מהרה תצמח" Then your light will burst out like the dawn and your healing will speedily sprout, as well as the words of Dovid HaMelech,"אז ימלא שחוק פינו ולשוננו רינה" Then our mouths will be filled with laughter and our tongue with glad song. With hopeful eyes we see the light of redemption shining through the darkness of exile.
On his death bed, Yaakov calls his sons and tells them "האספו ואגידה לכם את אשר יקרה אתכם באחרית הימים" assemble yourselves and I will tell you what will befall you in the End of Days. Yaakov wished to reveal to his children when the קץ will be, the end of exile, to strengthen and encourage them that their salvation is close to coming. But the שכינה, the Divine Presence, departed from him and he was not able to do so and the eyes and hearts of Bnei Yisrael darkened as a result.
The great sage Rabbi Shimshon of Ostropolya זללה"ה explained that Yaakov knew very well the secret rationale behind his children’s exile—to fix and atone for their sin of selling Yosef. Knowing this, Yaakov calculated that since nine brothers were involved in the selling of Yosef (Binyamin having remained at home and Reuven having been preoccupied with repenting for his sin) and because in selling Yosef the brothers had damaged the name of אהי' whose numerical value is twenty one (א=1 ה=5 י=10 ה=5), the total number of years they would have to be in exile would be twenty-one times nine, a total of 189 years. Yaakov reasoned that when 190 years had passed, their redemption would come. This is why Yaakov wanted to reveal the "קץ", the End of Days, to his children—the numerical value of ק"ץ being 190. Yaakov wished to do this, but could not, for the Divine Presence, the שכינה, had left him. Yaakov did not know that the brothers had included the שכינה in the selling of Yosef, making the total number of people ten, a minyan, in order to make an injunction incumbent on all those present at their tribunal, lest someone reveal what they had done. Because they actually numbered ten (nine brothers and the שכינה), the total number of years required in exile was 210, ten times the numerical value of G-d’s name אהי', 21. Therefore Bnei Yisrael’s redemption did not come until they had been in exile for 210 years.
When Moshe was commanded at the burning bush to go and redeem the people, he was bewildered because according to his calculation, the קץ was still far off. Moshe assumed that when the brothers added the שכינה to their tribunal, they did not damage the name אהי', but rather the name הוי', whose numerical value is not 21 but 26. This is how Moshe deduced 260 years, 26 times ten members of the tribunal which sold Yosef. Moshe could not understand how he could redeem the Jewish people if the time of redemption had not yet come. This is hinted to in the passuk "וירא ה' כי סר לראות" and Hashem saw that he [Moshe] had turned aside to see [the burning bush]. The numerical value of the word סר is 260. Hashem saw that Moshe’s calculation is סר, 260 years. So Hashem explained to Moshe that he erred in his calculation. Hashem said to Moshe, "כה תאמר לבני ישראל אהי' שלחני אליכם", tell Bnei Yisrael that אהי' has sent me to you. The reason for the exile is not because the Tribes has damaged the name הוי' but the name אהי', and therefore the exile is only 210 years, not 260 as Moshe had thought.
Go, says Hashem to Moshe, tell the people that the time has come and their redemption is near. Look and see that אהי' has sent me to you. He is with you in your suffering, and with you now to redeem you. He is with you in this hardship and will be with you in all others.
There are two psukim in this parsha whose subtle difference in phraseology reveals another aspect of exile and redemption. The one says"ויאמר עוד אלקים אל משה כה תאמר אל בני ישראל ה' אלקי אבותיכם אלקי אברהם אלקי יצחק ואלקי יעקב שלחני אליכם זה שמי לעלם וזה זכרי לדור דור"
G-d said further to Moshe, “So shall you say to the children of Israel, ‘Hashem, the G-d of your forefathers, the G-d of Abraham, the G-d of Isaac, and the G-d of Jacob, has dispatched me to you. This is My Name forever, and this is My remembrance from generation to generation.’
The very next passuk says "לך ואספת את זקני ישראל ואמרת אליהם ה' אלקי אבותיכם נראה אלי אלקי אברהם יצחק ויעקב לאמר פקד פקדתי אתכם ואת העשוי לכם במצרים"
Go and gather the elders of Israel and say to them, “Hashem, the G-d of your forefathers, has appeared to me, the G-d of Abraham, Isaac, and Jacob, saying, ‘I have surely remembered you and what is done to you in Egypt.’”
In the first Passuk, G-d assigns His name to each of the Patriarchs, אלקי אברהם אלקי יצחק ואלקי יעקב. In the second, G-d assigns His name to all three Patriarchs as one unit, אלקי אברהם יצחק ויעקב. Why do these two psukim differ?
This can be explained based on the following Gemara: The Gemara says that Eliyahu would frequent the Yeshiva of Rebbi. One day, it was Rosh Chodesh, Eliyahu was late in coming. When he finally did arrive, Rebbi asked him why he was late. Eliyahu explained that by the time I awoke Avraham, washed his hands, Avraham davened, and he laid him back to rest, and the same with Yitzchak and with Yaakov, it was already late. Rebbi asked Eliyahu, “can you not simply wake them all together (and wash all their hands together, have them all daven together, etc.)?” Eliyahu answered that if that would happen—if Avraham Yitzchak and Yaakov would daven at the same time—the force of their prayer would overwhelm the heavenly realms and would be so powerful, it would cause Mashiach to come prematurely.
The two aforementioned psukim are referring to two different exiles. The first passuk, where G-d’s name is assigned to each of the Avos— יצחק ואלקי יעקב אלקי אברהם אלקי—is referring to the final redemption as it says in that passuk וזה זכרי לדר דר זה שמי לעלם, this is My Name forever, and this is My remembrance from generation to generation. Because this passuk is referring to the final redemption, G-d did not assign his name to all the Avos together, because if all three would be joined in prayer, Mashiach would be here already. Rather, G-d assigns his name to each one individually, the G-d of Abraham, the G-d of Isaac, and the G-d of Jacob, each one on his own.
The next passuk is referring to the redemption from Egypt, as it says פקד פקדתי אתכם ואת העשוי לכם במצרים, I have surely remembered you and what is done to you in Egypt. Hashem was revealing to Moshe at the burning bush that even though the three Avos hadn’t joined forces in prayer to hasten the final redemption of their children, nevertheless they had already prayed for this current exile in Egypt, and nothing can prevent the power of their prayer from taking effect. Therefore, G-d instructs Moshe, go and tell Bnei Yisrael that I have remembered them and all that is being done to them in Egypt.
Let us plead before our Father in Heaven that he should command Eliyahu to awaken the three Avos in prayer together, so the words "לך ואספת את זקני ישראל ואמרת אליהם ה' אלקי אבותיכם נראה אלי אלקי אברהם יצחק ויעקב לאמר פקד פקדתי אתכם", Go and gather the elders of Israel and say to them, “Hashem, the G-d of your forefather has appeared to me, the G-d of Abraham, Isaac, and Jacob, saying, ‘I have surely remembered you’” come true speedily in our days. May we merit seeing wonders as we did when we left Egypt.
 הלכות יסודי התורה פ"ו ה"ב
 שבועות ל"ה ע"א
 For further insight see the full Ramban on this passuk
 שמות ג':ט"ו
 שמות ד': ל"א
 ברכות ס"ד ע"א
ישעיהו מ"ח: ח'
 תהלים קכ"ב: ב'
 The זוהר explains this point further, as does the אריז"ל SOURCE?. For further insight, see the commentary of the אור החיים on Parshas Vayechi SOURCE?
 שמות ג':ד'
 שמות ג': ט"ו
 שמות ג':ט"ז
בבא מציעא פ"ה ע"ב