New International Version 2 Peter 2:5
if he did not spare the ancient world when he brought the flood on its ungodly people, but protected Noah, a preacher of righteousness, and seven others;
Reporting not supporting but here are some comments by non-jws
A Silent Preacher and His Faith
In 2 Peter 2:5, Noah is described as a “preacher of righteousness.” In what way was he a preacher? The Greek word kerux (κηρυξ) refers to a herald, or “one who announces.” Even when he wasn’t saying anything, his labor on the Ark would have been his witness. However, some Jewish scholars maintain that Noah did indeed leave some words, too. John Gill, in chapter 22 of the Pirke R. Eliezer, quotes Noah’s words according to Jewish tradition: “Be ye turned from your evil ways and works, lest the waters of the flood come upon you, and cut off all the seed of the children of men.”
Q. I've heard it taught that Noah warned the world about the flood, but I can't find that in the Bible. On the contrary, Jesus says in Matthew 24 that the flood was a surprise to the world. Why do people believe Noah warned the earth?
A. The Biblical record provides only a glimpse of Noah's activities in the days leading up the flood, and most of the narrative in Genesis is focused on his work in building the ark. Nevetheless, we can make a reasonable assumption that Noah preached about the coming flood to his neighbors and community during the 100 years required to complete the ark.
First, we know from Genesis 6 that Noah was a blameless man, which means he lived a godly lifestyle before others. Furthermore, 2Peter 2 tells us Noah was a preacher of righteousness:
2Pet. 2:5 and did not spare the ancient world, but preserved Noah, a preacher of righteousness, with seven others, when He brought a flood upon the world of the ungodly;
Knowing that Noah was a preacher proclaiming God's truth in some form to the people of his day and given his godly character, we can assume Noah preached about the approaching flood and the need to repent. Furthermore, offering the world such a warning would be in keeping with God's character, since God typically gives opportunity for repentance prior to His judgments.
If Noah did warn the world, the world obviously chose to ignore his warnings, because the Bible teaches that the world was taken by surprise when the flood came. The fact that the world was caught off guard by the flood does not prove that Noah never preached concerning the coming judgment. It only tells us that the world paid no attention to the warnings.