Now Sarai, Abram’s wife, had borne him no children. But she had an Egyptian maidservant named Hagar; so she said to Abram, “The LORD has kept me from having children. Go, sleep with my maidservant; perhaps I can build a family through her.” Abram agreed to what Sarai said.

Genesis 16:1–2

So Hagar bore Abram a son, and Abram gave the name Ishmael to the son she had borne. Abram was eighty-six years old when Hagar bore him Ishmael.

Genesis 16:15–16