Genesis 16:1-3

1And Sarai Abram's wife did not bear him [children]. And she had an Egyptian maidservant; and her name was Hagar.

2And 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.

3And 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.