Hebrews 11:7

By faith Noah, being warned of God
In the Greek text, Noah is called "Noe", and so the Septuagint interpreters of the Old Testament call him; but Josephus calls him "Noeos": or "having received an oracle from God"; in which he was admonished, how to make an ark, as Moses was, in like manner, how to make a tabernacle, ( Hebrews 8:5 ) . This oracle or warning is extant, in ( Genesis 6:13-22 ) and it was

of things not seen as yet;
as the universal deluge; the building of an ark or ship, which was the first that ever was in the world; the entrance of all creatures into it; their preservation in it, and the destruction of all without it: and this divine warning, or oracle, concerning things of such a nature, delivered to Noah, and received by him, shows that he was a favourite of God; that his faith rested in the word of God; and that it agreed with the apostle's definition of faith, ( Hebrews 11:1 ) ,

moved with fear;
not with a fear of his own damnation; nor with a distrust of the salvation of himself and his family in the ark; but with an awful sense of the judgments of God upon the wicked; and with reverence of God, from whom he received the oracle; and with a religious fear, with which he worshipped God, and which he discovered by a regard to his word and ordinances; and which fear does not arise from nature, but from grace; and is increased by the discoveries of divine love; and is consistent with faith, goes along with it, and is a fruit of it: hence he

prepared an ark for the saving of his house.
Immediately, and without delay, he set about the building of the ark, and made it exactly according to the pattern which was given him; and his end in it was to secure his family, himself and his wife, his three sons and their wives, from the flood, which he believed would shortly come upon the world, according to the word of God; and in this his faith was seen: and from hence it may be observed, that, though God can save without means, yet, generally speaking, it is his will to save by them; and that as God saved Noah and his family in the waters, so he can, and does, save his people in afflictions; and also, that true faith is attended with obedience:

by the which he condemned the world:
the inhabitants of the world, the world of the ungodly: as a preacher, he declared they would be condemned, in case of impenitence and unbelief; and his words heard, and his actions seen by them, were aggravations of their condemnation; for by his works, as well as by his words, he reproved, and condemned them; by building the ark, as he declared his own faith, so he condemned their unbelief; (See Gill on Matthew 12:41)

and became heir of the righteousness which is by faith:
not of the law, but of the righteousness of Christ, and of eternal life through that; for he was not only heir of this world, as Abraham, but of that which is to come; and not through works of righteousness done by him, but through the righteousness of Christ received by faith, or through faith in Christ, the antitype of the ark.