Genesis 38:2-10

2And Judah saw there a daughter of a certain Canaanite whose name was Shua, and he married her and went in to her.

3So she conceived and bore a son, and he called his name Er.

4She conceived again and bore a son, and she called his name Onan.

5And she conceived yet again and bore a son, and called his name Shelah. He was at Chezib when she bore him.

6Then Judah took a wife for Er his firstborn, and her name was Tamar.

7But Er, Judah’s firstborn, was wicked in the sight of the Lord, and the Lord killed him.

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.