Charles Ellicott Commentary Psalms 66:17

"I cried unto him with my mouth, And he was extolled with my tongue." — Psalms 66:17 (ASV)

And he ... —Literally, exaltation (i.e., praise) was under my tongue, apparently a Hebrew idiom akin to our “on the tip of the tongue,” i.e., ready at any moment for utterance.