Genesis 38:8-10

8 Y'hudah said to Onan, "Go and sleep with your brother's wife - perform the duty of a husband's brother to her, and preserve your brother's line of descent."
9 However, Onan knew that the child would not count as his; so whenever he had intercourse with his brother's wife, he spilled the semen on the ground, so as not to give his brother offspring.
10 What he did was evil from ADONAI's perspective, so he killed him too.

Genesis 38:8-10 Meaning and Commentary

INTRODUCTION TO GENESIS 38

This chapter is wholly taken up with matters relating to Judah, the fourth son of Jacob, from whom the Jews have their name, and from whom Christ sprung: it treats of his marriage with a Canaanitess, his children by her, their character and end, Ge 38:1-11; of his incest with his daughter-in-law, though unknown by him, Ge 38:12-23; of his resentment against her, when he heard she was with child, and his confusion when he found it was by himself, Ge 38:24-26; and of the birth of twins by her, named Pharez and Zarah, Ge 38:27-30.

Complete Jewish Bible Copyright 1998 by David H. Stern. Published by Jewish New Testament Publications, Inc. All rights reserved. Used by permission.