Some time afterward, God put Abraham to the test. He said to him, "Abraham," and he answered, "Here I am." and He said, "Take your son, your favored one, Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the heights that I will point out to you...
They arrived at the place of which God had told him. Abraham built an altar there; he laid out the wood; he bound his son Isaac; he laid him on the altar, on top of the wood. And Abraham picked up the knife to slay his son. Then an angel of the LORD called to him from heaven: "Abraham! Abraham!" And he answered, "Here I am." And he said, "Do not raise your hand against the boy or do anything to him. For now I know that you fear God, since you have not withheld you son, your favored one, from Me" ...
"...The Lord declares: Because you have done this and have not
withheld your son, your favored one, I will bestow
My blessing upon you and make your descendants as numerous as the
stars of heaven and the sands on the seashore... All the nations
of the earth shall bless themselves by your descendants,
because you have obeyed My command."
(The Torah -- Genesis 22:1-2, 9-12, 16-18)