James 5:12

But above all things, my brethren, swear not, either by Heaven, or by earth, or by any other oath; but let yours be "the yes, yes," and "the no, no"; that ye fall not under condemnation.

Matthew 5:33-37

"Again ye heard that it was said to the ancients, You shall not swear falsely, but shall perform to the Lord your oaths;"

Matthew 23:16-22

"Woe to you, blind guides, who say, 'Whosoever swears by the temple, it is nothing; but whosoever swears by the gold of the temple, he is a debtor!'

1 Corinthians 11:34

If any one is hungry, let him eat at home, that ye come not together unto judgment. And the rest I will set in order, when I come.

2 Corinthians 1:17-20

When, therefore, I was purposing this, did I manifest fickleness or the things which I purpose, do I purpose according to the flesh, that with me there should be the "Yea, yea," and the "Nay, nay?"

James 3:1-2

My brethren, become not many of you teachers, knowing that we shall receive the greater judgment.

1 Peter 4:8

above all things, having fervent love among yourselves, because love covers a multitude of sins;

3 John 1:2

Beloved, I pray that, in all things, you may be prosperous, and be in health, even as your soul prospers.

Treasury of Scripture Knowledge

Summary

But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation.

Bible References

Above

1 Peter 4:8
above all things, having fervent love among yourselves, because love covers a multitude of sins;
3 John 1:2
Beloved, I pray that, in all things, you may be prosperous, and be in health, even as your soul prospers.

Swear not

Matthew 5:33
"Again ye heard that it was said to the ancients, You shall not swear falsely, but shall perform to the Lord your oaths;"
Matthew 23:16
"Woe to you, blind guides, who say, 'Whosoever swears by the temple, it is nothing; but whosoever swears by the gold of the temple, he is a debtor!'

But

2 Corinthians 1:17
When, therefore, I was purposing this, did I manifest fickleness or the things which I purpose, do I purpose according to the flesh, that with me there should be the "Yea, yea," and the "Nay, nay?"

Lest

James 3:1
My brethren, become not many of you teachers, knowing that we shall receive the greater judgment.
1 Corinthians 11:34
If any one is hungry, let him eat at home, that ye come not together unto judgment. And the rest I will set in order, when I come.