Genesis 49:4

Unstable as water. Reuben is characterized by a threefold designation: (1) his position in the family as Jacob’s first-born, (2) his relation to Jacob as his might and the beginning of his strength, (3) the natural pre-eminence that belonged to him as the eldest. Nevertheless, the advantages normally accruing to Reuben as Jacob’s first-born were to be taken from him because of the weakness of his character. The word translated “unstable,” literally, “a boiling over” of water, implies, figuratively, giving in to one’s emotions. Another form of the same root word is used in Judges 9:4 and Zeph. 3:4 for frivolity and pride. Jacob thus described the moral weakness of Reuben’s character, by which he forfeited the privileges as a first-born. Though, specifically, his crime consisted in committing fornication with Bilhah, his father’s concubine (Gen. 35:22), his later history gives evidence of a fundamental instability of character. This basic weakness disqualified him from becoming a leader, for leadership often calls for firmness and determination.

Thou shalt not excel. By the withdrawal of the rights of the first-born, Reuben lost the leadership of Israel. His tribe never attained a position of influence in the nation (see Deut. 33:6). Not one prominent personality emerged from the descendants of Reuben — no judge, no king, no prophet. Leadership was transferred to Judah, and the double portion to Joseph (1 Chron. 5:1, 2).