Ramban to Beresheet 42:9
And Yosef remembered the dreams - concerning them, and now knew that they had been fulfilled, for they had bowed down to him. This is the language of Rashi.
Now since he did not see Benjamin with them, he conceived of the strategy of devising a charge against them so that they would also bring his brother Benjamin to him, in order to first fulfill the first dream. It is for this reason that he did not wish to tell them at this time, I am Joseph your brother, and to say, Hasten and go up to my father, and send wagons, as he did to them the second time, for in that case his father would undoubtedly have come at once. It was only after fulfillment of the first dream that he told them, I am Joseph your brother, etc., in order to fulfill the second dream.
Were it not for this consideration, Yosef would indeed be regarded as having committed a great sin: bringing anguish to his father, leaving him for many days in the position of being bereft and mourning for Simeon and him. Even if it was his intention to cause his brothers minor anguish, how did he not have compassion for his elderly father? But he assigned each to its proper time in order to fulfill the dreams, knowing that they would truly be fulfilled.
Also, the second matter, which he effected against them in connection with the goblet, is not to be interpreted as if his intention was to cause them anguish, but rather because he suspected that they might hate Binyamin as a result of their jealousy of him on account of his father’s love for him, just as they were jealous of Yosef. Perhaps Binyamin had sensed that they had harmed Yosef, thus causing a quarrel and hatred to erupt between him and his brothers. Therefore, Yosef did not wish Binyamin to travel with them until he had tested their love for him, lest they harm him.
Similarly I say that all these acts of Yosef are accounted for by his wisdom in the interpretation of the dreams. Otherwise, one should wonder: After Yosef stayed in Egypt for many years and became chief and overseer in the house of a great lord in Egypt, how was it possible that he did not send a single letter to his father to inform him of his whereabouts and comfort him, as Egypt is only about a six-day journey from Hebron? Even if it were a year’s journey, out of respect to his father, he should have notified him, in which case even if the ransom of his person would be ever so costly, he would have redeemed him.
But it was because Yosef saw that the bowing down of his brothers, as well as his father and all his family, could not possibly be accomplished in their homeland, and he was hoping that it would be effected in Egypt when he saw his great success there. This was all the more so after he heard Paroh’s dream, from which it became clear to him that all of them were destined to come there, and all his dreams would be fulfilled.
Rav Yoel Bin Nun
The usual solution, advanced by the Ramban that Yosef was trying to fulfill the dreams, is rejected by R. Bin-Nun, chiefly because it doesn't address, in his opinion, the moral question. How could Yosef have left his father in torment, only to bring his dreams to fruition? Our entire outlook on this story changes, however, if we accept the fact that Yosef did not know that his brothers had fooled his father with the coat, the blood, and the lie that Yosef had been devoured by wild animals. Such thoughts never occurred to him! Hence it was Yosef who spent thirteen years of slavery in Egypt and, the following years of greatness wondering: "Where is my father? Why has no one come to look for me?" All the factors are now reversed, when seen from Yosef's point of view. Egypt is, after all, close to Canaan, and Yaakov was a rich, important and influential man, with international familial and political connections. The Midianites or Yishmaelites who brought Yosef to Egypt were his cousins; is it possible that no one from that caravan could be located in all those years? We know that Yaakov does not search for his son, as he thinks Yosef is dead, but Yosef has no way of knowing this.
Rav Yaaov Medan's critique of Rav Bin Nun
This thesis of Yosef's suspicion towards his father is untenable. Yosef knew that he was, after all, his father's favorite son and that his father had made him the striped coat. He also knew that his father had loved Rachel most of all his wives. Above all, would a man like Yaakov behave deceitfully, sending Yosef to his brothers on the false pretext of ascertaining their well-being, intending in fact that they sell him as a slave? Is there a son who would suspect his father of such a deed? This assumption is totally unrealistic.
It also remains unclear why Yosef, surprised that his father did not seek him out, came to harbor the kind of suspicions attributed to him by R. Bin-Nun. How could he be certain that his father knew of the sale, but refrained from searching for him? Why did it not occur to him that his father regarded him as dead? To this day, a person who disappears without a trace is presumed dead. Why should we assume that Yosef did not believe that the brothers were lying to his father? It was precisely because the brothers did not habitually report their actions to their father that Yosef found it necessary to tell his father all their misdeeds.
Rav Medan's Solution
Abarbanel offers the following explanation for Yosef's not contacting his father while in Egypt: "Even after Yosef tested his brothers by accusing them of espionage, he was still not certain whether they loved Binyamin or whether they still hated Rachel's children, so he focused on Binyamin to see whether they would try to save him." Yosef's behavior is part of an overall scheme to test the brothers and provide them with an opportunity to fully repent for selling him into slavery. The sin of Yosef's brothers is one of the more serious sins related in the book of Beresheet. Both the Torah and the Prophets equate this sin of selling a free man into bondage with the gravest of sins. The penitence of Yosef's brothers is not an incidental event appearing as part of another story, but a major theme of the narrative.
Rav Bin Nun
After carefully reading Rabbi Medan's detailed arguments, I nevertheless maintain that my presentation of the events is the correct one. There is clearly a process of repentance and rectification on the part of Joseph's brothers, and this is our guide to understanding the affair. But all this is God's plan. All Rav Medan's evidence proving a process of teshuva and restoration is correct; but there is no reason to credit Yosef with this. The challenge of repentance offered the brothers regarding Binyamin is a challenge issuing from God. Yosef was forever acting according to natural, human considerations.