Genesis 38:8-10

8And Judah said to Onan, “Go in to your brother’s wife and marry her, and raise up an heir to your brother.”

9But Onan knew that the heir would not be his; and it came to pass, when he went in to his brother’s wife, that he emitted on the ground, lest he should give an heir to his brother.

10And the thing which he did displeased the Lord; therefore He killed him also.