New Defender's Study Bible Notes
11:7 Noah. The writer here not only affirms the historicity of Noah but also of the ark and the worldwide Flood (see notes on Genesis 6–9 for extensive discussion of the evidence and its significance).
11:7 not seen as yet. The world had never even seen rainfall, or a river flood, let alone a global flood (Genesis 2:5), yet Noah believed God’s word and set about building a huge ark on dry land that would have been completely useless and unnecessary in a local flood. He and his family could easily have migrated to another region if it were to be a local flood, and so could the animals.
11:7 fear. Noah was not fearful for his own life, but for the lives and souls of his descendants if they continued to live in the violent and ungodly antediluvian society of the day. Hence he built an ark “to the saving of his house.” Because of his obedience, not only was he saved, but so was his family (see Genesis 7:1; compare Acts 16:31).
11:7 righteousness which is by faith. He, like all others who truly believe God’s Word, received His imputed righteousness by faith. This particular verse is the only one in Hebrews 11 that both begins and ends “by faith.”