The Torah says Jacob refused to be comforted and declared he would go down to the grave mourning. Targum Pseudo-Jonathan on (Genesis 37:35) adds a heartbreaking line the Hebrew only hinted at: And Isaac his father also wept for him.
Isaac was still alive. He outlived his son Esau's estrangement, outlived Rebekah, outlived Jacob's twenty years with Laban. And now, ancient and blind in Hebron, he heard that his grandson Joseph had been torn apart by a beast. He wept.
But here is the secret the Targumist is quietly telling us. The sages taught that Isaac, like Jacob, possessed Ruach ha-Kodesh — the Holy Spirit. He too should have been able to see, as Jacob did, that Joseph was still alive. Why then did he weep?
Because Isaac wept for Jacob, not for Joseph. He saw that his son was inconsolable, and he could not tell him the truth — because the decree from heaven was that Joseph's fate remain hidden, and even a patriarch cannot overrule heaven's timing. So Isaac, seeing further than Jacob, stayed silent, and wept beside him.
This is one of the most wrenching scenes in the entire Torah. A grandfather knowing, a father grieving, and the knowledge unshareable between them. Isaac's tears were not for the grandson he would see restored. They were for the son he could not console.
The Targum teaches that sometimes love means crying with someone while holding a truth you cannot yet tell. The beit ha-kever — the house of the grave — that Jacob spoke of was made more bearable only by the silent, weeping company of the one who knew better and said nothing.