And Er, Judah's firstborn, was wicked in the sight of the Lord,.... That is, exceedingly wicked, as this phrase signifies, Ge 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, Ge 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 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, Ac 5:5; or by sending some distemper, which quickly carried him off, as a token of his displeasure at his sin.
Abulpharag. Hist. Dynast. p.