Genesis 38:7-11

7But Er, Judah’s firstborn, was wicked in the Lord’s sight; so the Lord put him to death.

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

9But Onan knew that the child would not be his; so whenever he slept with his brother’s wife, he spilled his semen on the ground to keep from providing offspring for his brother.

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

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