Midrasch zu Jeschijahu 3:25

(Devarim, Ibid.) "And his men will be counted": "heroic" in strength; "heroic" in Torah. "heroic in strength": viz. (Isaiah 3:25): "Your men will fall by the sword, and your strong ones in the war." "heroic" in Torah: viz. (Psalms 103:20) "heroic" in strength, doing His word (Torah)." And (I Chronicles 5:6) "Be'erah was his son, who was exiled by Tiglath-Pilneser, king of Asher. He was the leader of the Reuvenites." Thus, Reuven shall live and he shall not die."