Genesis 38:9
King James Version
“And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother’s wife, that he spilled on the ground, lest that he should give seed to his brother.”
Context
6And Judah took a wife for Er his firstborn, whose name Tamar.
7And Er, Judah’s firstborn, was wicked in the sight of the LORD; and the LORD slew him.
8And Judah said unto Onan, Go in unto thy brother’s wife, and marry her, and raise up seed to thy brother.
9And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother’s wife, that he spilled on the ground, lest that he should give seed to his brother.
10And the thing which he did displeased the LORD: wherefore he slew him also.
11Then said Judah to Tamar his daughter in law, Remain a widow at thy father’s house, till Shelah my son be grown: for he said, Lest peradventure he die also, as his brethren And Tamar went and dwelt in her father’s house.
12And in process of time the daughter of Shuah Judah’s wife died; and Judah was comforted, and went up unto his sheepshearers to Timnath, he and his friend Hirah the Adullamite.