A moment of profound transformation occurs as years of heavy grief and disbelief suddenly give way to absolute certainty and overwhelming joy. The brothers relay Joseph's detailed promises to sustain the family through the remaining years of famine, vividly describing his immense power and greatness in Egypt [רשב״ם, ספורנו, העמק דבר]. However, this comprehensive report notably omits the dark truth of how Joseph arrived there. In fact, Jacob never learns that his own sons sold their brother. Until his dying day, he believes Joseph simply wandered astray in the field and was kidnapped. The brothers conceal the betrayal out of fear of their father's curse, while Joseph, driven by deep morality and humility, chooses never to reveal it [רמב״ן, רבנו בחיי, ביאור יש״ר].
The ultimate proof of the brothers' story arrives in the form of Egyptian wagons. On a practical level, these are royal and military vehicles that cannot leave Egypt without explicit permission from the highest authority. The sheer logistical effort required to send them proves beyond a doubt that Joseph holds absolute governmental power, as no one could orchestrate such a resource-heavy deception [רשב״ם, חזקוני, הדר זקנים, ביאור שטיינזלץ].
On a deeper level, the primary approach among commentators is that the wagons serve as a secret, intimate sign from Joseph, conceptually alluding to the biblical law of the decapitated calf. Decades earlier, when Joseph departed from his father in the valley of Hebron, Jacob insisted on escorting him. When Joseph urged his father to return home and spare himself the effort, Jacob refused. Instead, he taught his son the law of the calf, where city elders must declare that their hands did not shed a victim's blood. The underlying lesson is that failing to escort a traveler leaves them vulnerable, and neglecting this duty is akin to shedding blood. By sending the wagons, Joseph reminds his father of the very last subject they studied together, a private memory shared only between the two of them [רש״י, ריב״א, שפתי חכמים, גור אריה, דעת זקנים].
Furthermore, Joseph does not merely send the transport; he personally fulfills the Commandment of escorting travelers by accompanying his brothers as they leave Egypt. Since heavily guarded royal wagons require no protection from bandits, Jacob realizes that Joseph's escort is driven purely by a commitment to God's law. This profound realization assures Jacob that his son is not only physically alive but has remained deeply righteous and observant despite living in the Egyptian culture [כלי יקר].
Recognizing the undeniable truth, Jacob undergoes a complete revival. Physically and emotionally, he awakens from his initial shock and faintness. The heavy sadness that had extinguished his vitality for twenty-two years evaporates, replaced by a surge of life and joy [ספורנו, שד״ל, רלב״ג, בכור שור]. Spiritually, this restoration is even more significant. Prophecy and the Divine Presence can only rest upon a person who is in a state of joy, never one entrenched in sadness. Throughout his long mourning period, the prophetic spirit had completely departed from him. Now, comforted and joyous, the Divine Presence returns to him just as before [רש״י, רד״ק, רבנו בחיי, תורה תמימה, ברטנורא]. This spiritual return is also made possible because the divine ban of silence, an agreement shared by the brothers and the Divine Presence to conceal the sale of Joseph, is finally dissolved with Joseph's revelation [הטור הארוך].