testify

verb3

1. •
   to tell a court what someone knows about a case, after promising to tell the truth

   • One witness shall not testify against any person to cause him to die. — 1611
2. •
   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. — 1611
3. •
   To be evidence of.