Source: Genesis 12-22
After the Flood, Noah and his family and the animals that were in the ark began to spread out over the earth. It was not long before there were cities of people in many places around the world. One of these cities was called Ur, and a man named Abram lived in Ur with his wife Sarai. His father was Terah, who was the chief of a tribe of people. Terah moved his tribe from Ur to a city called Haran. When Terah died, God told Abram to move to a land that God would show him. Abram took part of the tribe with him, and God led Abram to the land of Canaan.
God promised that he would give the land of Canaan to Abram's descendants. However, there was a problem: Abram and Sarai had no children. In fact, not only did they have no children, but both Abram and Sarai were getting old and Sarai was past her child bearing years. God continued to promise a son to Abram and Sarai, but none came. Finally, when Abram was ninety-nine years old, God told Abram it was time for the promised son to come. God changed Abram's name to Abraham, which means "father of a multitude", and God changed Sarai's name to Sarah, which means "princess".
Soon after their names were changed, Sarah became pregnant. When Abraham was one hundred years old, Sarah gave birth to a son they named Isaac. Abraham and Sarah delighted in their son, and Isaac grew into a fine young lad. Then God gave Abraham a test. God told Abraham to take Isaac, whom Abraham loved, and offer him as a sacrifice to God.
Abraham rose up early the next morning, and took Isaac and two servants with him. They traveled for three days, until they saw the mountains of Moriah. Abraham told the two servants to stay behind while he and Isaac went on into the mountains. As they traveled into the mountains, Isaac asked his father where the lamb for the sacrifice was. Abraham replied that "God will provide himself a lamb for the burnt offering". They came to the place for the sacrifice, and Abraham built the altar. He laid the wood on the altar, and then bound Isaac his son and laid him on the altar.
Abraham prepared to sacrifice his son, and the angel of the Lord called to him out of heaven. The angel told Abraham not to sacrifice Isaac, "for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me". Abraham looked up and saw a ram caught by his horns in a nearby bush. Abraham took the ram and offered it up as a sacrifice instead of Isaac.
Then the angel of the Lord called to Abraham a second time. 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". Because of Abraham's obedience, all the earth has indeed been blessed, because the Savior of the world, Jesus Christ, came and ministered among Abraham's and Isaac's descendants.