Genesis 22: 1 - 2, 9 - 13, 15 - 18
1 After these things God tested Abraham, and said to him, "Abraham!" And he said, "Here am I."
2 He said, "Take your son, your only son Isaac, whom you love, and go to the land of Mori'ah, and offer him there as a burnt offering upon one of the mountains of which I shall tell you."
9 When they came to the place of which God had told him, Abraham built an altar there, and laid the wood in order, and bound Isaac his son, and laid him on the altar, upon the wood.
10 Then Abraham put forth his hand, and took the knife to slay his son.
11 But the angel of the LORD called to him from heaven, and said, "Abraham, Abraham!" And he said, "Here am I."
12 He said, "Do not lay your hand on the lad or do anything to him; for now I know that you fear God, seeing you have not withheld your son, your only son, from me."
13 And Abraham lifted up his eyes and looked, and behold, behind him was a ram, caught in a thicket by his horns; and Abraham went and took the ram, and offered it up as a burnt offering instead of his son.
15 And the angel of the LORD called to Abraham a second time from heaven,
16 and said, "By myself I have sworn, says the LORD, because you have done this, and have not withheld your son, your only son,
17 I will indeed bless you, and I will multiply your descendants as the stars of heaven and as the sand which is on the seashore. And your descendants shall possess the gate of their enemies,
18 and by your descendants shall all the nations of the earth bless themselves, because you have obeyed my voice."

EWTN