Jacob Could Not Believe Them
Then they went up out of Egypt and came [to] the land of Canaan, to Jacob their father. Then they told him, Joseph still is alive, and indeed he is ruler over all the land of Egypt. Then his heart became numb, because he did not believe them. So they spoke to him all the words of Joseph which he had spoken to them. Then he saw the wagons that Joseph had sent to carry him. So the spirit of their father Jacob revived. And Israel said, It is enough! Joseph my son is still alive. I will go and see him before I die. — Genesis 45:25-28 (my translation)
When Jacob's sons revealed to him the news about Joseph, Jacob did not respond with the overflowing joy and warmth of feeling that we would have expected. Rather, the text states that "his heart became numb" (literally, "cold"). He became non-responsive, so that he seemed "stunned" (NIV) or paralyzed. Why? "Because he did not believe them."
Jacob was a man of faith, who had seen God's faithfulness and, allowing for his weaknesses and failings, lived a life of trusting in God's promises. Yet, he had lived a life that was full of much suffering, grief, and disappointment. There was his flight from home, and all the sorrows and difficulties involving his relationship with Laban and his two wives. His situation seemed to have turned around, when he moved back home, and was met cordially by Esau. But then came the fiasco with the Shechemites, when his daughter Dinah is raped. This leads to a chain of treachery on the part of two of his sons, who use deceit to loot and destroy an entire city. Eventually Jacob's most beloved son, in whom he had obviously been placing his greatest hopes for the future, was taken away, and he spent years in grieving, thinking Joseph has died a brutal death. Then, Jacob's wealthy and prominent family finds themselves in the same situation as everyone else, on the verge of starving to death from the great famine. Then he loses another son for a while, and finally has to part with Benjamin, who is his most beloved son following the loss of Joseph.
So, when Jacob is confronted unexpectedly with the joyful news about Joseph, he is unable to receive it. There has been too much pain, too much disappointment. It throws him into a state of insensitivity and he is physically incapacitated.
Jacob, it seems, had come to a place in his life where he found it difficult to believe that God could be good to him. Though not abandoning his faith, and still following God, yet he had given up looking for the light at the end of the tunnel. In his great sufferings, he had become cynical, and almost could not receive the joyful news, looking for yet another wave of pain and disappointment. Ironically, years before he had accepted without question the dubious story of Joseph's death (obviously having not read many Agatha Christie novels); but now he could not believe the story of Joseph's being alive, even though there is no plausible reason his sons could or would have made up such a story.
It is possible for believers, in the process of enduring long trials of suffering, grief, or disappointment, to come to a place where they have trouble believing in the goodness of God, or at least believing that God desires to do good for them personally. We find ourselves, for example, being surprised to see answers to our own prayers. Or we imagine some God who perpetual delights in giving us hopes, only to disappoint them.
Though Jacob had trouble believing it, God was in fact working out a happy and joyful end to the sufferings of Jacob and his family, and it was all part of a grand plan God was working out for his people, according to his own timing and plan. When Jacob saw the wagons, he opened up his heart, and his spirit revived, as he started to see God's good plan coming together.
As believers, we must cling stubbornly to the hope and confidence that we have in God's goodness, faithfulness, and wisdom, and his control over the events of our lives. Whatever the disappointments or difficulties, we must continue to trust God, and believe that God is leading us toward something gloriously joyful and wonderful in the end.
"His heart became numb": וַיָּ֣פָג לִבּ֔וֹ (wa-yā-fog li-bō). Mansoor: וַיָּ֣פָג is Hiphil perfect of פּּוּג (pūg). It is not perfectly clear to me from this idiom exactly what the physical effect was on Joseph, as opposed to describing his mental or emotional reaction. HALOT lists this version under sense "to turn cold", but also references metaphorical usage in Habakkuk 1.4. A common literal translation (e.g., WEB) is "heart fainted". Many modern translations give something similar to NIV's "Jacob was stunned". In my survey, it seems like all translations generally, excepting translations made from foreign languages like Aramaic and the LXX, support the idea that Jacob was non-responsive initially because he could not or would not believe the report. ISV gives "Jacob didn't believe them, because he had become cynical".
[his] spirit [...] revived: וַתְּחִ֕י ר֖וּח (wat-hē rūḥ). Though not the same verb, cp. Judges 15.19, where Samson's spirit returns to him, i.e., he revives when near death from thirst and exhaustion. There is a lot of overlap and ambiguity in HALOT over the various senses of ר֖וּח, doubtlessly reflecting the complicated usage of the word in Scripture. But see HALOT sense 1, breath, and sense 6, breath which support life, or spirit. וַתְּחִ֕י: is Qal shortened imperfect of חָיָה (ḥā-yoh), to live, with Waw consecutive (Mansoor).
"it is enough!": רַ֛ב (rav) means much, many. As an exlamation it can mean "it is enough!" or "let it be enough!" (Mansoor). Interpretive translations generally give something similar to "I'm convinced!" (NIV) or "it must be true" (NLT).
"I will go": אֵֽלְכָ֥ה (˒il-khoh) has the paragogic ה, sometimes added for emphasis.