Phrases or words you don’t have to say so you don’t hurt your interlocutor

Watch what you say, so you don’t hurt your interlocutor.

The phrase “As I said before” seems harmless, but it has a subtext: already spoke, and you were not heard, and have to repeat it.
It’s better to do without this phrase and just repeat what you said before.

“Knew it would happen.”
That’s how we signify that we are more discerning than the other. And that’s not unambiguous at all.

“With all due respect.”
This phrase, by definition, can’t be benevolent: after it, people often say things that the other person would hate to hear.

“Just a reminder.”
Sounds like a kick, even if you didn’t mean anything by it. Omit the beginning and say right away what you meant.