This highly momentous day was when all of humanity began to be wiped out, and a remnant of eight people was delivered. But this “bone day” also reflects back on something earlier: a proclamation God gave. You can find it in Genesis 6:3. There, God allotted mankind 120 years. He was not limiting each person’s life to 120 years, because numerous people lived more than 120 years. Instead, as the New English Translation has it, “[Mankind] will remain for 120 more years.” It was at that point that Noah found grace, that he was divinely warned by God, and he became a preacher of righteousness.
So, this “bone day,” this very same day when Noah and his family entered the ark, looks back on the day of God’s determination to destroy mankind and deliver Noah. And if you notice in verse 11, God gives the specific month and day. The record is highly exact, and if it follows the pattern we saw in Exodus 12, and we remember God’s precision, it indicates that this was the same calendar date, 120 years after God said, “My Spirit shall not strive with man forever.” “They will remain for 120 more years.” So, the date of Noah entering the ark remains as a memorial of God’s words and deeds, 120 years before.