Genesis 38:8-11

8Then Judah said to Onan, “Sleep with your brother’s wife. Perform your duty as her brother-in-law and produce offspring for your brother.”

9But Onan knew that the offspring would not be his, so whenever he slept with his brother’s wife, he released his semen on the ground so that he would not produce offspring for his brother.

10What he did was evil in the Lord’s sight, so he put him to death also.

11Then Judah said to his daughter-in-law Tamar, “Remain a widow in your father’s house until my son Shelah grows up.” For he thought, “He might die too, like his brothers.” So Tamar went to live in her father’s house.