Click on Sons of Yaakov for a general introduction to the lives of these individuals who constituted the original Jewish People.
Reuven is the first-born son of Yaakov and Leah. His mother, who is less-loved than her sister and co-wife, Rachel (The Torah will later forbid the marrying of two sisters at the same time), feels the sting of that fact throughout her life, as is seen in the names that she gives her sons. In the case of Reuven, the Chumash says “Leah conceived and bore a son, and she called his name Reuven, for she declared, ‘Because HaShem has discerned (ra’ah) my humiliation; now my husband will love me.” (Bereshit 29:32)
In “Birchot Yaakov,” Yaakov says, “Reuven, you are my firstborn, my strength and my initial vigor, foremost in rank and foremost in power.” (Bereshit 49:3) You should have had all the blessings of the firstborn – first in inheritance, first with regard to kingship, and first with regard to service of HaShem in the Temple. But you have a fatal flaw; “Impetuous as water, you cannot be foremost...”
The first time we see Reuven acting in a manner not befitting his position in the family is after the death of Rachel. We find the following verses, where Yaakov is referred to as Israel, “Israel journeyed on, and he pitched his tent beyond Migdal-Eder. And it came to pass... that Reuven went and lay with Bilhah, his father’s concubine...” (Bereshit 35:21-22) That would be an unbelievable act if it were literally true. Therefore, Rashi, based on the Gemara in Shabbat 55b, explains what happened as follows: “...When Rachel died, Yaakov moved his bed, that had been placed in the tent of Rachel, into the tent of her handmaiden, Bilhah. Reuven came and contested this shaming of his mother. He said, ‘If my mother’s sister was her rival, that’s one thing, but that her handmaiden should be a rival as well, that is intolerable!’ Therefore, he moved his father’s bed to his mother’s tent.” (Rashi 35:22, text beginning “He mixed up”) Because Reuven entered into matters that were none of his business, the Torah used such strong language to describe his act.
Another time we see Reuven in action or, better, inaction, is when the brothers of Yoseph are considering how to treat him as he approaches them in Dotan. Shimon and Levi suggest that they kill him for his inexcusable behavior towards the brothers, but Reuven will have none of that. “Reuven hears the plan and he rescues him, and he says, ‘We will not kill him with our hands.’ And Reuven further says to them, ‘Do not shed blood; rather, throw him into this pit in the Wilderness, but do not strike him with your hand...’ ” (Bereshit 37:22) But Reuven’s intention was not to leave him there to die, according to the testimony of the Torah itself, according to Rashi, but rather “...it was for the purpose of saving him from their hands, and to return him to his father.” Then Reuven leaves the scene temporarily, for reasons debated in the Midrash. But in his absence, a caravan of Ishmaelite traders passes by and the brothers, at Yehudah’s suggestion, sell Yoseph to them. “Reuven returned to the pit and behold, Yoseph was not in the pit! And he tore his garments. He returned to the brothers and said, ‘The lad is not here, and I, where shall I go?’ ” (Bereshit 37:29-30) Here we have another occasion when Reuven acted inappropriately for the eldest of the brothers. If his intention was to return Yoseph to his father, he should not have feared his brothers’ response, and carried out his intention!
Another occasion where Reuven falls short is when Yoseph, now viceroy of Egypt, has accused the brothers of spying. He has demanded that they not return without Binyamin, the youngest of the brothers. Yaakov hesitates to send Binyamin, fearing a recurrence of the tragedy of Yoseph. Reuven then says to Yaakov, “You can kill my two sons if I fail to return him to you...” (Bereshit 42:37) Yaakov’s response is, “...My son will not go down with you...” (Bereshit 42:38), and Rashi’s comment is, “He did not accept the suggestion of Reuven, saying ‘This is a foolish firstborn. He says I could kill his sons. Are they indeed his sons, and not also mine?’ ” (Rashi on Bereshit 42:38)
For the reasons mentioned above, Yaakov demotes Reuven from his leadership role, but retains him among the ranks of his sons. Moshe Rabbeinu, in VeZot HaBerachah, also prays, “Let Reuven live and not die, and may his numbers be great!” (Devarim 33:6)
In the Book of Shophtim, we find an account of a great battle between Israel and Canaan. Some of the Tribes of Israel act heroically and some Tribes just procrastinate. The Tribe of Reuven is in the latter category. Devorah sings mockingly “Among the divisions of Reuven, great were the deliberations!” (Shophtim 5:15)
The Bible tells us, in its portrait of Reuven, of a tragic figure who could have been king, but due to a weakness in his personality, was demoted from that greatness.