Genesis 38:8-11

And Judah said unto Onan, Go in unto thy brother’s wife, and perform the duty of a husband’s brother unto her, and raise up seed to thy brother. And Onan knew that the seed would not be his; and it came to pass, when he went in unto his brother’s wife, that he spilled it on the ground, lest he should give seed to his brother. And the thing which he did was evil in the sight of Jehovah: and he slew him also. Then said Judah to Tamar his daughter-in-law, Remain a widow in thy father’s house, till Shelah my son be grown up; for he said, Lest he also die, like his brethren. And Tamar went and dwelt in her father’s house.