Genesis 22:4

“Then on the third day, etc.] After he had received the command from God, and from his setting out on his journey; for he had now travelled two days, Mount Moriah being forty miles from Beersheba, where Abraham dwelt f1264; or, as others compute it, forty: Hebron f1265 was twenty miles from Beersheba, and Jerusalem twenty two from Hebron; and to travel twenty miles a day on foot, as Isaac and the servants seem to have done, there being but one ass among them, was far enough in those hot countries. Now all this while Abraham had time to reconsider things in his mind, and deliberate thoroughly what he was going about; and by proceeding in it, after he had such leisure to revolve things in his…”

“on the third day Abraham lifted up his eyes, &c.--Leaving the servants at the foot [Gen 22:5], the father and son ascended the hill, the one bearing the knife, and the other the wood for consuming the sacrifice [Gen 22:6]. But there was no victim; and to the question so naturally put by Isaac [Gen 22:7], Abraham contented himself by replying, "My son, God will provide himself a lamb for a burnt offering." It has been supposed that the design of this extraordinary transaction was to show him, by action instead of words, the way in which all the families of the earth should be blessed; and that in his answer to Isaac, he anticipated some substitution. It is more likely that his words were…”