Genesis 38:7-9

Modern English Version

⁷ But Er, Judah’s firstborn, was wicked in the sight of the Lord, so the Lord killed him.

⁸ Then Judah said to Onan, “Go have relations with your brother’s wife, and marry her, and raise up descendants for your brother.” ⁹ But Onan knew that the descendant would not be his, so when he had relations with his brother’s wife, he let his semen go on the ground, so that he would not give a descendant to his brother.