James 5:12

But above all, my brethren, swear not; neither by heaven, nor by the earth, nor any other oath: but let your yea be yea, and your nay nay; that ye may not fall under condemnation.

Matthew 5:33-34

Again, ye have heard, that it was said to the ancients, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:

Treasury of Scripture Knowledge

Summary

And ye shall not swear by my name falsely, neither shalt thou profane the name of thy God: I am the LORD.

Bible References

Ye shall

Matthew 5:33
Again, ye have heard, that it was said to the ancients, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:
James 5:12
But above all, my brethren, swear not; neither by heaven, nor by the earth, nor any other oath: but let your yea be yea, and your nay nay; that ye may not fall under condemnation.