Genesis 38:9-11

Amplified Bible, Classic Edition

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.

¹⁰ And the thing which he did displeased the Lord; therefore He slew him also.

¹¹ Then Judah said to Tamar, his daughter-in-law, Remain a widow at your father’s house till Shelah my [youngest] son is grown; for he thought, Lest perhaps [if Shelah should marry her] he would die also, as his brothers did. So Tamar went and lived in her father’s house.