to swear; to vow; to take an oath; to pledge
to pledge allegiance; to swear an oath of allegiance; to take an oath of allegiance
to make a joint vow; to swear together; to pledge
to make a vow; to take an oath
before God; as God is my witness; in the name of God
surely; upon my word; by Jove; (with neg) by no means; never