What is the wise saying that illustrates spelling of ou sound?

There's no single wise saying specifically dedicated to spelling the "ou" sound. However, the common mnemonic for remembering the different ways to spell the "ou" sound is:

"When you see 'ou' think of 'cow' and 'house'."

This is because "ou" can be pronounced as the long "o" sound (as in "cow," "house") or the short "u" sound (as in "could," "would").

There are other ways to spell the "ou" sound, such as "ow" (as in "now") or "ough" (as in "though"), which further complicates the issue.

Overall, there's no one-size-fits-all solution for remembering the spelling of the "ou" sound. You need to learn it through practice and exposure to different words.