Genesis 38:6-10

Judah and Tamar

⁶In the course of time, Judah arranged for his firstborn son, Er, to marry a young woman named Tamar. ⁷But Er was a wicked man in the Lord’s sight, so the Lord took his life. ⁸Then Judah said to Er’s brother Onan, “Go and marry Tamar, as our law requires of the brother of a man who has died. You must produce an heir for your brother.”

⁹But Onan was not willing to have a child who would not be his own heir. So whenever he had intercourse with his brother’s wife, he spilled the semen on the ground. This prevented her from having a child who would belong to his brother. ¹⁰But the Lord considered it evil for Onan to deny a child to his dead brother. So the Lord took Onan’s life, too.