harsh words make the going rough; consider your words
Proverb meaning that even something naturally round can be made square depending on how you cut it; used to caution that the way you speak can change outcomes, so choose your words carefully.
As the saying goes, 'a round egg can be cut into a square,' so be careful how you phrase things.
A traditional Japanese proverb. The literal image is that a round egg can be cut to appear square, illustrating that presentation and approach can change the nature of things.