And make not God's (name) an excuse in your oaths against doing good, or acting rightly, or making peace between persons; for God is One Who heareth and knoweth all things. (2:224)

Fulfil the Covenant of God when ye have entered into it, and break not your oaths after ye have confirmed them; indeed ye have made God your surety; for God knoweth all that ye do. (16:91)

And be not like a woman who breaks into untwisted strands the yarn which she has spun, after it has become strong. Nor take your oaths to practise deception between yourselves, lest one party should be more numerous than another: for God will test you by this; and on the Day of Judgment He will certainly make clear to you (the truth of) that wherein ye disagree. (16:92)

And take not your oaths, to practise deception between yourselves, with the result that someone's foot may slip after it was firmly planted, and ye may have to taste the evil (consequences) of having hindered (men) from the Path of God, and a Mighty Wrath descend on you. (16:94)

Verily those who plight their fealty to thee do no less than plight their fealty to God: the Hand of God is over their hands: then any one who violates his oath, does so to the harm of his own soul, and any one who fulfils what he has covenanted with God,- God will soon grant him a great Reward. (48:10)