Exodus 23:13 "Make no mention of the name of other gods"

At times, a person may be required to take an oath in court, in order to show that he is telling the truth.

When the oath is given, the person will choose to swear in the name of something that is holy and important to him. This helps to convince others that he is sincere.

We are not allowed to swear in the name of any idol or G‑d.

If we are dealing with someone who believes in idols, we are forbidden to allow him to take an oath using the name of the idol.