Genesis 38:1

It was at that time that Jehuda had gone down from his property, and separated himself from his brethren, and had inclined to a man an Adullemite whose name was Hira,

ויהי בעת ההיא, והמדנים מכרו אותו, [the Torah contrasts the facts with the perception of the facts, i.e. Joseph was alive but the Midianites had sold him. I believe that this is why the author quotes the beginning of this verse without elaborating on it at all. He leaves it to our imagination to fill in this next item in the tragic chain of errors beginning with the fact that Yitzchok had shown more love for Esau. Ed.] at about the same time when Joseph was sold to Egypt at the suggestion of Yehudah who had proposed this instead of bringing him back to his father and had thereby bereaved his father, Yehudah reaped some of the fruit of his ill advised plans, in that the way was paved for him to be bereaved of two of his own sons in due course.

ויהי בעת ההיא וירד יהודה, after Joseph had been sold. The fact that the Torah speaks of וירד, “he descended,” seems to imply that Dotan was situated at a much higher elevation than Adulam. According to a Midrash quoted by Rashi, the word וירד does not refer to a physical descent but to the brothers having demoted Yehudah from his role of their leader as they held him responsible for the debacle with Joseph. They had repented their part in the whole episode, and they accused Yehudah of not having been firm enough. Just as they had listened to him when he told them not to kill Joseph, they claimed that they would have listened to him if he had suggested that they should bring him back to their father. In Bereshit Rabbah 85,2 the whole paragraph commencing with וירד יהודה until the beginning of chapter 39 is considered as not relevant to the story, at least not at this point. Why then did the Torah insert this episode here thereby spoiling our concentration on what would happen to Joseph? According to Rabbi Eliezer the Torah wanted to create a conceptual link between one “descent,” and another “descent.” Rabbi Yochanan justifies the “interruption,” by linking one הכר נא “please identify!” to another הכר נא. Yehudah had deceived his father with these words, whereas Tamar reminded Yehudah that he had been deceived by her and that his assumption that she was a harlot who had become pregnant by her customer was totally unfounded.(compare 37,2 and 38,25 respectively)

ויט עד איש עדולמי, he pitched his tent and let his flock graze in the proximity of this town Adulam; eventually he struck up a friendship with the man חירם described in our verse.

וירד יהודה, “Yehudah descended;” our sages explained that this choice of words by the Torah means that Yehudah’s brothers, who up until then had considered him as their leader and spokesman, demoted him on account of the sale of their brother Joseph and the anguish this had caused their father. (B’reshit Rabbah, 85,1) Ibn Ezra questioned this, seeing that only twenty two years elapsed between the sale of Joseph and the reunification of the brothers with him and the family’s moving to Egypt. We know that Joseph had been seventeen years old when he had been sold; we also know that he was thirty years old when he interpreted Pharaoh’s dream; we further know that the family descended to Egypt in the second year of the famine, i.e. nine years after Joseph had been appointed viceroy of Egypt. If you count the years from the time Yehudah got married to the daughter of the man described earlier until the descent of the whole family with Yehudah at their head more than twenty two years must have passed. If we count a year each for the time Yehudah’s wife was pregnant with each of her three sons, and add the years after Onan’s death during which Shelah grew to maturity, i.e. was old enough to get married, you already have accounted for 16 years. Add a year till Peretz could have been born and you have accounted for already 17 years. Even if you were to assume that Peretz was no more than 7 years old when he became the father of Chetzron and another year for the birth of his brother Chamul, all of whom are listed in Genesis chapter 46 as having come to Egypt with Yaakov and Yehudah, you already have accounted for 25 years not 22. One would have to say that when Shelah was described as having “grown” up, the Torah refers to his having become 9 years old, at which age it is possible to produce semen fit to sire a child. We can find support for this from the Talmud, tractate Niddah, folio 45, where the Mishnah discusses a nine year old who performed the levirate marriage ceremony on his sister-in-law whose husband had died without having had any children, that he cannot give such a sister-in-law a decree of divorce until he reaches the age of 13, as a minor cannot divorce his wife. Moreover, the original marriage of his deceased brother had been a marriage in the full sense of the word, and what he did was only to substitute for his deceased brother, so that any divorce cannot be less complete than that. According to an opinion quoted in the Talmud tractate Sanhedrin, folio 69, there were periods in former eras when seven year old males were able to impregnate females with their semen.