Genesis 6:3

3And God said: “My spirit shall not remain in man forever, because he is flesh. And so his days shall be one hundred and twenty years.”
6:3 His days shall be, etc: 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)
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