ויאסר יוסף מרכבתו ויעל לקראת ישראל אביו גשנה וירא אליו ויפל על צואריו ויבך על צואריו עוד.
“Yosef harnessed his chariot and went to greet his father Yisrael in Goshen. He appeared before his father, and fell in tears upon his shoulder.”
After they were finally reunited after so many years, Yosef cried upon his father’s shoulder, but Yaakov did not cry upon Yosef’s. Rashi explains that instead Yaakov recited Shema.
It is amazing to consider Yaakov’s self-control at this poignant moment. Yosef was his favorite son, whom he had presumed dead for twenty-two years. All that time, he refused to be consoled, insisting that he would descend to his grave in misery over the loss of his son. How great must have been the outburst of his emotion when he exclaimed, “My son Yosef still lives! I shall go to see him before I die.” Words cannot express the wonderful joy and excitement he must have felt. And yet when he finally saw his son, he contained his emotion. He did not embrace and kiss his long lost son. He did not even utter a word of greeting. He simply recited Shema; the same Shema we all recite twice each day.
The difference is that for Yaakov, Shema was no mere mechanical routine; no chore or religious duty to be dispensed with before we can get on with our day. For him, it was an outpouring of emotion, even more powerful than his reunion with his son. For him, the words, “You shall love Hashem your G‑d with all your heart,” were not just an issue of theological conviction, but a most profound emotional experience.
The Sefer HaChinuch comments on the mitzva to love Hashem:
ראוי לו לאדם שישים כל מחשבתו וכל מגמתו אחר אהבת השם, ויעריך בלבו תמיד כי כל מה שהוא בעולם מעושר ובנים וכבוד, הכל כאין וכאפס ותוהו כנגד אהבתו ברוך הוא, וייגע תמיד כל היום בבקשת החכמה למען ישיג ידיעה בו, סוף דבר יעשה כל יכלתו להרגיל מחשבות לבו כל היום באמונתו ויחודו עד שלא יהי רגע אחד ביום ובלילה בהקיצו שלא יהא זוכר אהבת אדוניו בכל לבו.
A person should focus all his thoughts and desires on the love of Hashem. He should constantly develop in his heart the understanding that all the pleasures of this world, including wealth, family, and honor, are all meaningless compared to the love of Hashem. He should strive for the wisdom to recognize this, and train his thoughts to revolve around the awareness of Hashem’s Unity, until he passes not even one moment by day or by night, without thinking about his love for his Master, which consumes his entire heart.
Yaakov’s love for Hashem was the single dominant motivation in his life. Therefore, all other emotions paled in comparison. The Maharal adds that Yaakov’s love for Hashem was inspired to even greater heights when he was granted the wish for which he had never dared hope. The Maharal writes:
כאשר בא יעקב וראה את יוסף בנו מלך, בא בלבו אהבתו ויראתו של הקב"ה איך מדותיו הם טובות ושלימות, ומשלם שכר טוב ליראיו. וזהו מדת החסידים אשר יקרה להם טוב מתדבקים אל הקב"ה על הטובות והאמת שעשה עמהם. וזהו קריאת שמע שבו נזכר ייחוד מלכות שמים ואהבתו. וראוי היה לקרות קריאת שמע כאשר בא אליו יוסף אחר הצער הגדול אשר היה לו בעבורו, ועתה ראה אותו מלך, היה אוהב את הקב"ה אשר עושה לו זה, וקבל מלכותו ואהבתו ויראתו.
When Yaakov saw his son ruling over Egypt, his heart was overcome with love and awe of Hashem. He was struck by the recognition of how much kindness Hashem had done for him, and how He so generously rewards those who serve Him. In this way, the pious are inspired by the happy events of their lives to draw closer to Hashem.
It was only fitting that Yaakov recite Shema when he was finally reunited with Yosef. He had suffered so much sorrow during Yosef’s absence. Now that he saw Yosef as king, he felt love for Hashem Who had granted him such joy. Therefore, Yaakov recited Shema, to accept Hashem’s sovereignty and declare his love and awe of Him.
Yaakov lived a difficult life, in which he had to contend with one misfortune after another. He was hounded by his twin brother, abused by his deceitful father-in-law, and bereaved by the loss of Yosef for twenty-two tragic years, in which the Shechinah was hidden from him. Yet in the end of his life he merited a period of joy and nachas the likes of which he had never known. The Shechinah had returned to rest upon him, and his happiness knew no bounds.
The Tanna D’Vei Eliyahu describes this last stage of Yaakov’s life:
מיד נתגלגלו רחמיו של הקב"ה, ונתן לו הקב"ה שבע עשרה שנה סמוך לזקנותו טובה ...יעקב אבינו היה בטובה לשבע עשרה שנה והעלה עליו הקב"ה כאילו כל ימיו בטובה, שנאמר ויחי יעקב בארץ מצרים וגו'.
Hashem’s mercy was extended towards Yaakov, and He granted him seventeen good years with which to conclude his life. Yaakov Avinu enjoyed the last seventeen years of his life, and thus it became as if his entire life had been good, as it is written, “And Yaakov lived in the land of Egypt.”
The Tanna D’Vei Eliyahu interprets the expression “Yaakov lived,” to mean that he lived a happy, vivacious life, the likes of which he had never known. He was surrounded by his beloved family, all of them toiling in Torah study, with his successful and righteous son caring for all their needs. Therefore, he saw this as the most appropriate opportunity to express his love for Hashem, and his gratitude for all that Hashem had done for him. He finally merited to see an end to his suffering, and realize that all his hardships had been for the best.
This realization is uniquely expressed by Shema. The Name “Hashem” refers to His attribute of mercy, while the Name “Elokim” refers to His attribute of justice. Sometimes our eyes deceive us, making it seems as if His justice is unmerciful. For this reason, the Klausenberger Rav zt”l taught that we cover our eyes when we say, “Hashem Elokeinu, Hashem Echad,” to affirm that His mercy and justice are inseparable, even though we cannot always see how this is true.
It was this realization that was perfectly evident to Yaakov, as he merited to see his son alive and well, and all his hardships vanish into thin air. Therefore, it was only fitting that he choose that moment to recite Shema.
 Bereishis 46:29
 Bereishis 45:28
 Sefer HaChinuch 418
 Gur Aryeh
 Bereishis 47:28; Tanna D’Vei Eliyahu Rabbah ch. 6