Genesis 38:6 - Coke's Commentary on the Holy Bible

Genesis 38:6, &c. Name was Tamar— It is not said who or of what family Tamar was, though it is most probable she was a Canaanitess; nor does it appear what was the crime of Er; enormous enough, no doubt, to draw down so exemplary a punishment from God. It is plain, from this transaction, that the practice which Moses afterwards enacted into a law, Deuteronomy 25:5 was of ancient standing: the same custom prevailed among the AEgyptians. The crime of Onan shews a peculiarly malignant disposition, Deuteronomy 25:9.; and it is probable, that bad as it was in itself, yet his sin was aggravated with a worse circumstance, viz. his having an eye to the suppressing of the MESSIAH's birth, since he should not have the honour to be numbered among his ancestors, which might provoke GOD to cut him off. See Univ. Hist. Acts of self-pollution were always held peculiarly criminal, even by heathen moralists. The Hebrew doctors looked upon them as a degree of murder.