And Sarai Abram's wife did not bear him [children]. And she had an Egyptian maidservant; and her name was Hagar.
References for Genesis 16:1
And Sarai said to Abram, Behold now, Jehovah has shut me up, that I do not bear. Go in, I pray thee, to my maidservant: it may be that I shall be built up by her. And Abram hearkened to the voice of Sarai.
And Sarai Abram's wife took Hagar, the Egyptian, her maidservant, at the end of ten years that Abram had dwelt in the land of Canaan, and gave her to her husband Abram, as his wife.
And he went in to Hagar, and she conceived. And when she saw that she had conceived, her mistress was lightly esteemed in her eyes.
And Sarai said to Abram, My wrong be on thee! I have given my maidservant into thy bosom; and now she sees that she has conceived, I am lightly esteemed in her eyes. Jehovah judge between me and thee!
And Abram said to Sarai, Behold, thy maidservant is in thy hand: do to her what is good in thine eyes. And Sarai oppressed her; and she fled from her face.
And the Angel of Jehovah found her by a spring of water in the wilderness, by the spring on the way to Shur.