Genesis 38:6-8

International Standard Version

⁶ Judah found a wife for his oldest son Er. Her name was Tamar. ⁷ But the Lord considered Er, Judah’s oldest son, to be wicked—so he put him to death. ⁸ So Judah instructed Onan, “You are to have sexual relations with your dead brother’s wife, performing the duty of a brother-in-law with her, and have offspring for your brother.”