Tafsiran Kejadian 22:8: Rashi, Bekhor Shor, Chizkuni & Radak

יראה לו השה — this means as much as: He will look out for and choose a lamb for Himself, and if there will be no lamb for a burnt offering, then, בני MY SON will be the offering. Although Isaac then understood that he was travelling on to be slain, yet.

God will see to the lamb for Him, my son: Meaning, my son [will be the lamb for the burnt-offering]. He said to him a matter with two meanings. For he said to him, the [other] one according to his understanding - [its] meaning was like one saying, "My son, the Holy One will see to the lamb for Him." But our Rabbis say (Bereishit Rabbah 56:4) that Yitzchak understood, and nevertheless, "the two of them went together" - with the same mind to fulfil the will of the Creator.

יראה לו השה לעולה, “He will select the lamb that should be the one to serve as the burnt offering.” Even though G-d had told him that his descendants would become known through his son Yitzchok (21,12), he was afraid that Ytzchok would be slaughtered. He had said to himself: “perhaps Yitzchok has already been intimate with a woman without my having been aware, and that woman had already given birth to a son or a daughter for him, so that G-d’s promise will be fulfilled even if he dies here.” After all Yitzchok was already 37 years old.

וילכו שניהם יחדיו THEY WENT BOTH OF THEM TOGETHER — with the same ready heart (Genesis Rabbah 56:4).