Genesis 38:1-4

And it came to pass at that time, that Judah went down from his brethren, and turned in to a certain Adullamite, whose name was Hirah.

And Judah saw there a daughter of a certain Canaanite, whose name was Shuah; and he took her, and went in unto her.

And she conceived, and bare a son; and he called his name Er.

And she conceived again, and bare a son; and she called his name Onan.