Hi I believe "wiser" would be correct in this case. You might also say "Wiser words have never been written." or "Wiser words could never be written." or colloquially you might say "Never a wiser word was said." I am not a grammar expert, just a native speaker so I may be incorrect but "wiser" sounds better to my ears :)

Hello, The grammatically correct version is 'wiser' but as this is a quote or saying it is possible to use 'more wise' as an alternative. Personally I would use "Wiser words will never be written." Best wishes Bob

Hi ! How are guys doing, everybody safe...very well I have a doubt about the word (Wise), I was writting another day, and it just came out in my mind, as i was doing a quote (Insights). So it is wise to say WISER or WISEST, which one is the correct or sounds better, because i would go with wisest, BUT i dunno. I've read the previously comments here and everyone is saying, that the correct form is WISER, i'll pick this, anyway thanks.