Genesis 38:7

And Er, Judah's firstborn, was wicked in the sight of the Lord,.... That is, exceedingly wicked, as this phrase signifies,

Genesis 13:13, was guilty of some very heinous sin, but what is not mentioned; according to the Targum of Jonathan and Jarchi, it was the same with his brother Onan's, Genesis 38:9, which it is suggested he committed, lest his wife should prove with child, and lose her beauty; but if it had been the same with his, it would have been expressed as well as his. An Arabic writer p says, that he cohabited with his wife not according to the course of nature, but in the "sodomitical" way:

and the Lord slew him; by his immediate hand, striking him dead at once, as Ananias and Sapphira were stricken, Acts 5:5; or by sending some distemper, which quickly carried him off, as a token of his displeasure at his sin.

p Abulpharag. Hist. Dynast. p. 16.