Bereshis 38:9-11

Orthodox Jewish Bible

⁹ And Onan knew that the zera should not be his; and it came to pass, when he went in unto eshet achiv, that he spilled it on the ground, lest he should give zera to achiv.

¹⁰ And the thing which he did was rah in the eyes of Hashem; therefore He slaughtered him also.

¹¹ Then said Yehudah to Tamar his kallah, Remain an almanah at thy bais avi, till Shelah beni is grown; for he said, Lest he die also, as his achim did. And Tamar went and dwelt in her bais avi.