John Calvin Commentary Genesis 9:8

"And God spake unto Noah, and to his sons with him, saying," — Genesis 9:8 (ASV)

And God spake unto Noah. So that the memory of the deluge would not inspire them with new terrors whenever the sky was covered with clouds, and to prevent the earth from being drowned again, this source of anxiety is removed. And certainly, if we consider the great propensity of the human mind to distrust, we will not deem this testimony to have been unnecessary, even for Noah.

He was indeed endowed with a rare and incomparable faith, even to a miraculous degree; but no strength of steadfastness could be so great that this most sad and terrible vengeance of God would not shake it. Therefore, whenever any great and continued shower seems to threaten the earth with a deluge, this barrier, on which the holy man can rely, is set in place.

Now, although his sons would need this confirmation more than he, yet the Lord speaks especially for his sake. And the clause that follows, ‘and to his sons who were with him,’ relates to this point. For how is it that God, in making His covenant with Noah’s sons, commands them to hope for the best?

Truly, this is because they are joined with their father, who is, so to speak, the principal party to the covenant, and are thus associated with him in a subordinate position. Moreover, there is no doubt that it was God’s design to provide for all his descendants. It was not, therefore, a private covenant made with only one family, but one that is common to all people and that will flourish throughout all ages until the end of the world.

And truly, since at the present time impiety overflows no less than in the age of Noah, it is especially necessary that the waters be restrained by this word of God, as by a thousand bolts and bars, so that they do not break forth to destroy us. Therefore, relying on this promise, let us look forward to the last day, when the consuming fire will purify heaven and earth.