Matthew Henry on Genesis 38:1-11
Here is, 1. Judah's foolish friendship with a Canaanite-man. He went down from his brethren, and withdrew for a time from their society and his father's family, and got to be intimately acquainted with one Hirah, an Adullamite, Gen 38:1. It is computed that he was now not much above fifteen or sixteen years of age, an easy prey to the tempter. Note, When young people that have been well educated begin to change their company, they will soon change their manners, and lose their good education. Those that go down from their brethren, that despise and forsake the society of the seed of Israel, and pick up Canaanites for their companions, are going down the hill apace. It is of great consequence…
Read the whole note in the consoleJamieson-Fausset-Brown on Genesis 38:8
Judah said unto Onan . . . marry her, and raise up seed to thy brother--The first instance of a custom, which was afterwards incorporated among the laws of Moses, that when a husband died leaving a widow, his brother next of age was to marry her, and the issue, if any, was to be served heir to the deceased (compare Deu 25:5).
Adam Clarke on Genesis 38:10
Wherefore he slew him also - The sin of Onan has generally been supposed to be self-pollution; but this is certainly a mistake; his crime was his refusal to raise up seed to his brother, and rather than do it, by the act mentioned above, he rendered himself incapable of it. We find from this history that long be fore the Mosaic law it was an established custom, probably founded on a Divine precept, that if a man died childless his brother was to take his wife, and the children produced by this second marriage were considered as the children of the first husband, and in consequence inherited his possessions.
John Gill on Genesis 38:10
And the thing which he did displeased the Lord,.... Being done out of envy to his brother, and through want of affection to the memory of his name; and it may be out of covetousness to get his estate into his own hands, and especially as it frustrated the end of such an usage of marrying a brother's wife; which appears to be according to the will of God, since it afterwards became a known law of his; and it was the more displeasing, as it was not only a check upon the multiplication of Abraham's seed as promised, but since the Messiah was to come from Judah. This was doing all to hinder it that lay in his power:
wherefore he slew him also; in like manner as he had slain his brother, Genesis…