Genesis 38:7-9

Amplified Bible, Classic Edition

⁷ And Er, Judah’s firstborn, was wicked in the sight of the Lord, and the Lord slew him.

⁸ Then Judah told Onan, Marry your brother’s widow; live with her and raise offspring for your brother.

⁹ But Onan knew that the family would not be his, so when he cohabited with his brother’s widow, he prevented conception, lest he should raise up a child for his brother.