James 5:12

But, my brethren, before all, swear not, neither by heaven, or by earth, or any other oath: but let your conversation be yes yes; and no no; lest you may fall under condemnation.

Matthew 5:33-34

Again you have heard that it was said to the ancients, Thou shalt not swear falsely, but shall 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 you have heard that it was said to the ancients, Thou shalt not swear falsely, but shall perform unto the Lord thine oaths.
James 5:12
But, my brethren, before all, swear not, neither by heaven, or by earth, or any other oath: but let your conversation be yes yes; and no no; lest you may fall under condemnation.