The Old Testament book named for the Moabite woman who became an ancestor of David is Ruth.
Ruth begins with a family from Bethlehem moving to Moab during a famine. After the deaths of her husband and father-in-law, Ruth remains loyal to her Israelite mother-in-law, Naomi, and travels with her to Bethlehem. There Ruth gleans in the fields of Boaz, a relative of Naomi’s deceased husband.
Boaz marries Ruth after fulfilling the family-redeemer obligations described in the story. Their son Obed becomes the father of Jesse, and Jesse becomes the father of David. This genealogy appears at the end of the book and connects a short family narrative with the royal line of Israel.
Ruth is sometimes confused with Esther because both are books named after women. They differ in setting, plot, and historical role: Ruth is set around Bethlehem and the period of the judges, while Esther centers on the Jewish community in the Persian Empire.