Matthew 5:34-37

But I tell you, when you make a promise, don’t try to make it stronger with a vow. Don’t make a vow using the name of heaven, because heaven is God’s throne. Don’t make a vow using the name of the earth, because the earth belongs to him. Don’t make a vow using the name of Jerusalem, because it also belongs to him, the great King. And don’t even say that your own head is proof that you will keep your promise. You cannot make one hair on your head white or black. Say only ‘yes’ if you mean ‘yes,’ and say only ‘no’ if you mean ‘no.’ If you say more than that, it is from the Evil One.