John Gill expounds on 1 Peter 3:20, discussing the disobedience of those in the days of Noah who ignored God's warnings and the preaching of Noah, leading to their destruction in the flood. He emphasizes God's longsuffering during the 120 years of ark preparation, where only eight souls were saved, illustrating the narrow path to salvation through faith in Christ, akin to entering the ark. Gill draws parallels between the flood's waters that saved Noah and his family and the Gospel's dual nature of salvation and judgment, encouraging believers to remain steadfast in their faith amidst trials.