Genesis 6:22

Thus did Noah - He prepared the ark; and during one hundred and twenty years preached righteousness to that sinful generation, 2 Peter 2:5. And this we are informed, 1 Peter 3:18, 1 Peter 3:19, etc., he did by the Spirit of Christ; for it was only through him that the doctrine of repentance could ever be successfully preached. The people in Noah's time are represented as shut up in prison - arrested and condemned by God's justice, but graciously allowed the space of one hundred and twenty years to repent in. This respite was an act of great mercy; and no doubt thousands who died in the interim availed themselves of it, and believed to the saving of their souls. But the great majority of the people did not, else the flood had never come.

The obedience of Noah and the accomplishment of his task are here recorded. The building of so enormous a fabric must have occupied many years.