We swear to one another because we’re proving that what we are saying is the honest truth – without doubt.
On the flip side, we swear because we believe the other person does not believe us.
It is not God’s will for us to swear. Therefore, swear not.
James 5:12 (KJV) – 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.