Isaac believed in God. He had been taught implicit obedience to his father, and he loved and reverenced the God of his father. He could have resisted his father if he had chosen to do so. But after affectionately embracing his father, he submitted to be bound and laid upon the wood. And as his father's hand was raised to slay his son, an angel of God, who had marked all the faithfulness of Abraham on the way to Moriah, called to him out of heaven, and said, “Abraham, Abraham: and he said, Here am I. And he said, Lay not thine hand upon the lad, neither do thou anything unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from Me. SR 82.2
“And Abraham lifted up his eyes, and looked, and behold behind him a ram caught in a thicket by his horns: and Abraham went and took the ram, and offered him up for a burnt offering in the stead of his son.” SR 83.1
Abraham had now fully and nobly borne the test, and by his faithfulness redeemed his lack of perfect trust in God, which lack led him to take Hagar as his wife. After the exhibition of Abraham's faith and confidence, God renewed His promise to him. “And the angel of the Lord called unto Abraham out of heaven the second time, and said, By myself I have sworn, saith the Lord, for because thou hast done this thing, and hast not withheld thy son, thine only son: that in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies; and in thy seed shall all the nations of the earth be blessed; because thou hast obeyed My voice.” SR 83.2