Abraham's story is told in Genesis 12:12-25. The text records his call from Ur, God's covenant with him, and the promise of descendants.
Key passages:
"Now the LORD had said unto Abram, Get thee out of thy country, and from thy kindred, and from thy father’s house, unto a land that I will shew thee:" — Genesis 12:1
"And he believed in the LORD; and he counted it to him for righteousness." — Genesis 15:6
"Neither shall thy name any more be called Abram, but thy name shall be Abraham; for a father of many nations have I made thee." — Genesis 17:5
"And he said, Take now thy son, thine only son Isaac, whom thou lovest, and get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of." — Genesis 22:2
Read the full narrative in Genesis.