2 Bible Verses about Covenant Obligations

Again, ye have heard, that it was said to them of old time, Thou shalt not forswear thyself, but shalt perform thine oaths unto the Lord. But I say unto you, Swear not at all, neither by heaven, for it is God's throne. Nor by the earth, for it is his footstool; neither by Jerusalem, for it is the city of the great King.read more.
Neither shalt thou swear by thy head; for thou canst not make one hair white or black. But let your conversation be yea, yea; nay, nay: for whatsoever is more than these, cometh of the evil one.

I speak after the manner of men: though it be but a man's covenant, yet if it be confirmed, none disannulleth or addeth thereto.