And thus is it written (Ibid. 35:22) "And it was, when Israel dwelt in that land, that Reuven went and lay with Bilhah, his father's concubine, and Israel heard." When Jacob heard this, he shuddered and said: Can it be that there is "base matter" in my sons! — until he was told by the L-rd that Reuven had repented, as it is written (Ibid.) "And the sons of Jacob were twelve" (including Reuven.) We are hereby taught that Reuven afflicted himself all of his days because of that act, until Moses accepted his penitence, viz. (Devarim 33:6) "Reuven shall live (in this world) and he shall not die" (in the world to come).