Reuben in Fausset's Bible Dictionary

Jacob's firstborn, Leah's son, born long after the marriage. The name expresses the parents' joy at the accomplishment of long deferred hope: "Behold ye a son" (Genesis 29:32). He gathered mandrakes for his mother, in boyhood (Genesis 30:14). (See MANDRAKES.) In a sudden gust of temptation he was guilty of foul incest with Bilhah, his father's secondary wife. Jacob on his deathbed (Genesis 49:3-4) said: "boiling over (so pachaz means) like water (on a rapid fire), thou shalt not excel" (Genesis 49:4). The effervescence of water symbolizes excited lust and insolent pride. By birthright Reuben was "the excellency of dignity and the excellency of power" (Genesis 49:3), i.e. entitled to the chieftianship of the tribes and to a double portion; but because of incest (Genesis 35:22; Leviticus 18:8) "thou shalt not excel" or "have this excellency" (compare the margin of Leviticus 4:7). (No great act, no great prophet, judge, or hero leader, springing from Reuben, appears on record (1 Chronicles 5:1-2.)...