Genesis 38:6-11

6Now Judah acquired a wife for Er, his firstborn, and her name was Tamar. 7But Er, Judah’s firstborn, was wicked in the sight of the LORD; so the LORD put him to death. 8Then Judah said to Onan, “Sleep with your brother’s wife. Perform your duty as her brother-in-law and raise up offspring for your brother.”

9But Onan knew that the offspring would not belong to him; so whenever he would sleep with his brother’s wife, he would spill his seed on the ground so that he would not produce offspring for his brother. 10What he did was wicked in the sight of the LORD, so He put Onan to death as well.

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