Quote
"ἡ γλῶσσ᾽ ὀμώμοχ᾽, ἡ δὲ φρὴν ἀνώμοτος"
"It is not the oath that makes us believe the man, but the man the oath."

Traditionally, an oath is a statement of fact or a promise taken by a sacrality as a sign of verity. A common legal substitute for those who object to making sacred oaths is to give an affirmation instead. Nowadays, even when there is no notion of sanctity involved, certain promises said out loud in ceremonial or juridical purpose are referred to as oaths. "To swear" is a verb used to describe the
"ἡ γλῶσσ᾽ ὀμώμοχ᾽, ἡ δὲ φρὴν ἀνώμοτος"
"Before Utu, I will not change my word."
"He that sweareth to his own hurt and changeth not."
"I say unto you, Swear not at all; neither by heaven; for it is Gods throne: Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King. Neither shalt thou swear by thy head, because thou canst not make one hair white or black. But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil."
"You can have no oath registered in heaven to destroy the Government; while I shall have the most solemn one to "preserve, protect, and defend" it."
"Juravi lingua, mentem injuratam gero."