The story of Joseph is interrupted in this chapter to expose the shamefulness of an important part of Judah's history. We have seen that Judah took the lead in selling Joseph as a slave. In fact, in every relationship of Judah his shame and dishonor is evident. He sold his brother, he deceived his father, he married a Canaanite wife, he had both his sons killed by the Lord for wickedness, he deceived his daughter-in-law when promising his son Shelah to her, then had two sons by the same daughter-in-law (unwittingly).
He pictures the tribe of Judah, which has had a deeply painful history over the ages, so that it will require the powerful work of the Holy Spirit in conjunction with the manifestation of the Lord Jesus in glory, to break down Judah's proud arrogance (Zechariah 12:7-14), just as we see Judah personally broken down when having to face Joseph in Genesis 44:18-34. In verse 1 Judah is seen leaving his brothers. The history of his brothers is not considered here, for Israel's long history has really been represented in the history of Judah since the ten tribes were separated from Judah and Benjamin. Judah's marriage to a Canaanite wife (v.2) symbolizes the nation's illicit commerce with Gentile business. For Canaan means "a trafficker," a principle contrary to true Christian character, but Israel has exchanged any spiritual values she had for the legal principle of trading or trafficking in the world's markets. Shuah's name means "riches," which the Jewish nation has sought as an object for centuries.
Three sons were born to Shuah, the first one killed by the Lord because of wickedness (v.7). The second, Onan, agreed to take the widow or Er as his wife in order to have a child that would be officially his brother's. But he did not complete his contract honorably, and the Lord considered this serious enough to kill him also (vs.8-10). The reason was his absolute selfishness, for the child would not be officially his (though actually so). These two cases illustrate the degrading history of the tribe of Judah. Shelah, the youngest son, is said to possibly mean "sprout," and indicates at least a preserved remnant that promises a miraculous revival for the nation Israel.
Judah promised Tamar that when Shelah was grown (for as yet he was only young), then she could marry him, meanwhile asking her to remain as a widow in her father's house. But we shall see that Judah failed to keep his promise, just as the tribe of Judah has constantly done
Eventually Judah's wife Shuah died, for "riches (the meaning of her name) take themselves wings; they fly away" (Proverbs 23:5). Judah was not driven to the feet of the Lord by this, but turned to the company of one whom he thought was a prostitute. He had promised to give his youngest son Shelah to Tamar, but had not kept his promise. She therefore took matters into her own hands and deceitfully posed as a prostitute to seduce Judah (vs.13-15). When he promised to send her a kid as payment for his fornication, she demanded some security, and he gave her three things that were unmistakably his property (v.18). From this one occasion she conceived a child.
Immediately she left the area and changed her clothes, resuming her widowhood state. Of course when Judah sent the kid, expecting to retrieve the pledge he had left, the messenger was not only unable to find the prostitute, but was told that no prostitute had even been in that place.
Tamar's plan worked as she had desired, and three months later Judah was told that she was pregnant through prostitution (v.24). He had no hesitation in condemning her, and passed sentence that she should be burned to death. Evidently he never even thought of the man who was involved in the case. Judah could sin without any question being raised, but he considered that for the very same sin Tamar must be killed!
Then Tamar exposed him, sending to him thee items of security he had given her, telling him she was pregnant by the owner of these things (v.25). Judah at least gave her credit for being more righteous than he (v.26), though rather, he was more guilty than Tamar, for righteousness was not involved in the matter at all.
Tamar gave birth to twins, one beginning to come first, but superseded by the other (vs27-29). This is another lesson of the first being last and the last first, as in the case of Esau and Jacob, and many others.
However, out of this shameful history it is amazing to think that God has seen fit to bring about marvelous blessing. For Judah, Tamar and Pharez are recorded as in the genealogy of the Lord Jesus in Matthew 1:3. In fact, Tamar is one of only four woman mentioned in that genealogy, -- Tamar, Rahab, Ruth and "her who had been the wife of Uriah" (Matthew 1:3-6). But this is intended to impress upon us the marvel of the pure grace of God in reaching guilty sinners in the gift of His holy, sinless Son!
There was no continued relationship between Judah and Tamar, and we have no record either of Tamar's subsequent history.