μεσιτεύω G3315
mesiteúō · mes-it-yoo'-o · Verb
from μεσίτης; to interpose (as arbiter), i.e (by implication) to ratify (as surety):--confirm.
1 Occurrence in the King James Bible
Hebrews 6:17Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath: