Genesis 6:3

Verse 3. His days shall be, and so forth The meaning is, that man’s days, which before the flood were usually 900 years, should now be reduced to 120 years. Or rather, that God would allow men this term of 120 years, for their repentance and conversion, before he would send the deluge. Challoner.—He spoke therefore to Noe in his 480th year. Saint Augustine—Those who suppose, that he foretold this event 20 years later, think with S. Jerom, that God retrenched 20 years from the time first assigned for penance. The Spirit of the sovereign Judge was fired with contending; or, as others translate it, with remaining quiet as in a scabbard, and bearing with the repeated crimes of men. He resolved to punish them severely in this world, that he might shew mercy to some of them hereafter. Saint Jerome 9. Hebrew Calmet.—If we suppose, that God here threatens to reduce the space of man’s life to 120 years, we must say, at least, that he did it by degrees; for many lived several hundred years, even after the deluge. In the days of Moses, indeed, few exceeded that term. But we think the other interpretation is more literal, and that God bore with mankind the full time which he promised. Worthington.