Yosef’s brothers hated him so much to the point that they wanted to kill him. Reuven implores them to throw Yosef into a pit instead, intending to save his younger brother later. In Genesis 37:30, it says that Reuven “returned to his brothers”. This led commentators to speculate that Reuven was not present when the brothers subsequently conspired to sell Yosef to the Ishmaelites. It could very well be that he was with the brothers all along and upon hearing of the plan to sell Yosef, he slips away in order to extricate him from the pit. He leaves his brothers on a rescue mission and after discovering an empty pit “returns” to his brothers to inform them that Yosef is missing.
Reuven was the oldest brother and although he always desired doing the right thing, was impulsive and not consistently persuasive and ultimately failed at saving Yosef from being sold and beginning a journey down to Egypt.
According to the Rashbam, the brothers never actually sold Yosef. While the brothers were sitting and eating, so distant from the pit that they could not hear Yosef’s cries, they lifted up their eyes and saw a caravan of Ishmaelites coming their way. At this point in time, Yehudah’s power of persuasion becomes evident. He devises a plan and suggests selling Yosef to the Ishmaelites instead of killing him. The brothers agree. While they waited for the Ishmaelites to arrive, Midianites passed by, found Yosef in the pit, pulled him out and sold him to the Ishmaelites unbeknownst to the brothers.
Only when Reuven surreptitiously went to retrieve Yosef did it become apparent that Yosef was gone. He then ran back to the brothers and informed them that Yosef was missing and they realized someone else must have taken him.
This is later supported in two places. In 40:15 when Yosef was in prison, he says that he was kidnapped from the land of the Hebrews.This seems to indicate that his brothers hadn’t sold him, rather foreigners had kidnapped him from the pit. In 37:36, immediately after we are told of Yaakov’s excessive mourning for Yosef and his refusal to be consoled, it says again that “the Midianites sold him to Egypt”. Perhaps the repetition here that it was the Midianites who sold Yosef is to point out that the brothers did not know of his whereabouts since they didn’t witness the sale. Therefore, despite the distress of Yaakov, they were unable to retrieve Yosef as they had no idea where he had been taken.
At this point, the narrative immediately begins the story of Yehudah and Tamar. It says, “Yehudah went down”, right after the selling of Yosef, indicating a connection between the stories. It is possible that Yehudah took the initiative to try and find Yosef. It seems that he has relocated to a place that is frequented by merchants. He befriends and becomes partners with Hirah the merchant and marries the daughter of a merchant. Later, Tamar sits at the crossroads where merchants pass in order to entice Yehudah. Perhaps Yehudah had hopes of meeting someone who knew something about the whereabouts of Yosef.
Yehudah had realized his error in that he had influence over his brothers, but didn’t do more to save Yosef. Although he did not find Yosef, this did not dissuade him from taking further steps towards rectification.
He was the one who convinces Yaakov to let Binyamin go down to Egypt by taking full personal responsibility for him. When Yosef wants to keep Binyamin prisoner for “stealing the goblet”, Yehudah steps up and fights for him. He argues with Yosef despite the negligible chances of changing a decree of the powerful viceroy. In fact, his plea is so successful that Yosef could not control himself any longer and finally reveals himself to his brothers with an emotional outburst.
Yehudah recognizes his failure in not saving Yosef from the pit. He expends great effort trying to rectify his mistake in order to bring the family back together. Yehudah’s willingness to literally stake his life in their youngest brother’s defense proves to their unrecognized and estranged brother that his family’s attitude has indeed changed. This shows that a desire to do the right thing along with perseverance can bring peace where there was once hatred.