testify

To make a declaration, or give evidence, under oath.

It was only after a decade away from Skipton that I was finally able to garner the courage to return and testify against my abuser.

One witness shall not testify against any person to cause him to die.

To make a statement based on personal knowledge or faith.

We speak that we do know, and testify that we have seen; and ye receive not our witness.

[T]he pleaſures of ſenſe have no reliſh vvhere thou [Jesus] irradiateſt and teſtifieſt vvith our conſcience, that vve are the children of God, and have done thy vvill ſincerely, […]

To be evidence of.

"Iberian-Sardinian" substrate features have been posited time and time again. These have usually been explained as testifying to a migration from the Iberian Peninsula to Sardinia in prehistoric times.