Sarah (originally Sarai) is a biblical matriarch, prophet, and major figure in Abrahamic religions. While different Abrahamic faiths portray her differently, Judaism, Christianity, and Islam all depict her character similarly, as that of a pious woman, renowned for her hospitality and beauty, the wife of Abraham, and the mother of Isaac. Sarah has her feast day on 1 September in the Catholic Church, 19 August in the Coptic Orthodox Church, 20 January in the LCMS, and 12 and 20 December in the Eastern Orthodox Church.

In the Book of Genesis 20:12, in conversation with the Philistine king Abimelech of Gerar, Abraham describes Sarah as both his wife and his half-sister ("my father's daughter, but not my mother's"). Such unions were later explicitly banned in the Book of Leviticus (Leviticus 18:9). However, some commentators identify her as Iscah (Genesis 11:29), a daughter of Abraham's brother Haran, and point out that Abraham's claim that she was his half-sister was a lie to avoid saying that she was his wife.

By her union with Abraham, Sarah had one child, Isaac. After her death, Abraham married Keturah, whose identity biblical scholars debate (that is, whether or not she was actually Hagar), and by her had at least six more children.

In the biblical narrative, Sarah is the wife of Abraham. In two places in the narrative he says Sarah is his sister (Genesis 12:10 through 13:1, in the encounter with Pharaoh, and Genesis 20, in the encounter with Abimelech). Knowing Sarah to be a great beauty and fearing that the Pharaoh would kill Abraham to be with Sarah, Abraham asks Sarah to tell the Pharaoh that she is his sister (Genesis 17).

She was originally called Sarai. In the narrative of the covenant of the pieces in Genesis 17, during which Yahweh promises Abram that he and Sarai will have a son, Abram is renamed as Abraham and Sarai is renamed as Sarah. According to most modern scholars, both Sarah and Sarai come from the same root SRR, with both meaning "important woman". A minority of scholars derive Sarai from the root SRY, meaning "contend with" or "withstand", similar to the name Israel.

Terah, with Abram (as he was then called), Sarai and Lot, departed for Canaan, but stopped in a place named Haran, where Terah remained until he died at the age of 205. Yahweh had told Abram to leave his country and his father's house for a land that he would show him, promising to make of him a great nation, bless him, make his name great, bless those who blessed him, and curse "him" that curses him. Following God's command, Abram took his wife Sarai, his nephew Lot, and the wealth and slaves that they had acquired, and traveled to Shechem in Canaan. Abram was 75 at this time.

There was a severe famine in the land of Canaan, so Abram and Lot and their households travelled south to Egypt. On the journey to Egypt, Abram instructed Sarai to identify herself only as his sister, fearing that the Egyptians would kill him in order to take his wife, saying,

I know what a beautiful woman you are. When the Egyptians see you, they will say, 'this is his wife.' Then they will kill me but will let you live. Say you are my sister, so that I will be treated well for your sake and my life will be spared because of you.