Genesis 38:26

‘And Judah acknowledged them and said, “She is more righteous than I inasmuch as I did not give her to Shelah my son.” And he knew her again no more.'

To his credit Judah acknowledges the truth of the situation and recognises that she is not guilty after all. She has only done what she had a right should be done, to bear a son to her late husband by a near kinsman. Had it not been for his failure to fulfil his promise it would have been, as it should have been, through his son. It is he who is the more guilty for he had failed in his duty to his late son.

Thus he accepts that she is now his wife by right of the levirate law although a wife with whom he feels he can no longer have sexual relations because she is also his daughter-in-law. This brings out the unusualness of the situation. It was not usual for the father to be the near kinsman. But Tamar's innocence is made clear, and we can have no doubt, for her sake and for the sake of her sons, that the verdict was made clear in written form. That is why the compiler later knew of this event.

And for Judah it was a time of shame and open admission of guilt. He could not deny that he had behaved very badly. What began with the cruel suggestion for the sale of Joseph into slavery results in this time of great shame for himself and his family.