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 to young people to choose proper associates; for these they will imitate, study to recommend themselves to, and, by their opinion of them, value themselves: an error in this choice is often fatal. 2. His foolish marriage with a Canaanite-woman, a match made, not by his father, who, it should seem, was not consulted, but by his new friend Hirah, Gen 38:2. Many have been drawn into marriages scandalous and pernicious to themselves and their families by keeping bad company, and growing familiar with bad people: one wicked league entangles men in another. Let young people be admonished by this to take their good parents for their best friends, and to be advised by them, and not by flatterers, who wheedle them, to make a prey of them. 3. His children by this Canaanite, and his disposal of them. Three sons he had by her, Er, Onan, and Shelah. It is probable that she embraced the worship of the God of Israel, at least in profession, but, for aught that appears, there was little of the fear of God in the family. Judah married too young, and very rashly; he also married his sons too young, when they had neither wit nor grace to govern themselves, and the consequences were very bad. (1.) His first-born, Er, was notoriously wicked; he was so in the sight of the Lord, that is, in defiance of God and his law; or, if perhaps he was not wicked in the sight of God, to whom all men's wickedness is open; and what came of it? Why, God cut him off presently (Gen 38:7): The Lord slew him. Note, Sometimes God makes quick work with sinners, and takes them away in his wrath, when they are but just setting out in a wicked course of life. (2.) The next son, Onan, was, according to the ancient usage, married to the widow, to preserve the name of his deceased brother that died childless. Though God had taken away his life for his wickedness, yet they were solicitous to preserve his memory; and their disappointment therein, through Onan's sin, was a further punishment of his wickedness. The custom of marrying the brother's widow was afterwards made one of the laws of Moses, Deu 25:5. Onan, though he consented to marry the widow, yet, to the great abuse of his own body, of the wife that he had married, and of the memory of his brother that was gone, he refused to raise up seed unto his brother, as he was in duty bound. This was so much the worse because the Messiah was to descend from Judah, and, had he not been guilty of this wickedness, he might have had the honour of being one of his ancestors. Note, Those sins that dishonour the body and defile it are very displeasing to God and evidences of vile affections. (3.) Shelah, the third son, was reserved for the widow (Gen 38:11), yet with a design that he should not marry so young as his brothers had done, lest he die also. Some think that Judah never intended to marry Shelah to Tamar, but unjustly suspected her to have been the death of her two former husbands (whereas it was their own wickedness that slew them), and then sent her to her father's house, with a charge to remain a widow. If so, it was an inexcusable piece of prevarication that he was guilty of. However, Tamar acquiesced for the present, and waited the issue.

And he was at Chezib when she bare him - This town is supposed to be the same with Achzib, which fell to the tribe of Judah, Jos 15:44. "The name," says Ainsworth, "has in Hebrew the signification of lying; and to it the prophet alludes, saying the houses of Achzib shall be (Achzab) a lie to the kings of Israel, Mic 1:14."

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

And Judah saw there a daughter of a certain Canaanite--Like Esau [Gen 26:34], this son of Jacob, casting off the restraints of religion, married into a Canaanite family; and it is not surprising that the family which sprang from such an unsuitable connection should be infamous for bold and unblushing wickedness.