Arabian Wisdom, by John Wortabet, , at sacred-texts.com
Koran. Be true to a covenant, for a covenant holds a man responsible. Be faithful to your pledged covenants and keep your oaths.
Traditions. A man who keeps not his word has no religion.
A true man's word is like an oath.
Be truthful in what you say, faithful to your promise, and careful of what is entrusted to you.
A pledged word is as if you had made the gift.
Proverbs. A true man keeps his promise.
A pledged word has the same value as a debt.
The promise of a true man is a greater obligation than a debt.
That man is a hypocrite who prays and fasts, but is untruthful in what he says, false to his word, and unfaithful in discharging a trust.