2 Corinthians 1:17-20

1:17 Therefore when I was planning to do this, I did not do so without thinking about what I was doing, did I? Or do I make my plans according to mere human standards so that I would be saying both “Yes, yes” and “No, no” at the same time? 1:18 But as God is faithful, our message to you is not “Yes” and “No.” 1:19 For the Son of God, Jesus Christ, the one who was proclaimed among you by us – by me and Silvanus and Timothy – was not “Yes” and “No,” but it has always been “Yes” in him. 1:20 For every one of God’s promises are “Yes” in him; therefore also through him the “Amen” is spoken, to the glory we give to God.

Colossians 4:6

4:6 Let your speech always be gracious, seasoned with salt, so that you may know how you should answer everyone.

James 5:12

5:12 And above all, my brothers and sisters, do not swear, either by heaven or by earth or by any other oath. But let your “Yes” be yes and your “No” be no, so that you may not fall into judgment.