Is there a verb for "telling the truth"? [closed]

Why is there no set word that means "to tell the truth"? We have a word for telling something that is not truthful, a.k.a. to lie, but why is there no conjugatable term for telling the truth?

In Latin, the word for truth is veritas. In English, we have words like verify, which means to validate the truth of something.

So why not have a word that means to tell the truth instead of saying "tell the truth"?

I'm telling the truth.

I'm X-ing.

There are a whole bunch of legal terms for this. All are fair game, but because we use the terms so rarely in spoken speech they sound stiff, formal, and long.

'Aver' is in the link referenced above. That's probably closest to what you ask.

'Represents' or 'warrants' (often combined into the phrase 'represents and warrants') means statement following is identified as truthful. 'Attest' also means to state something truthfully.