This summary is not the rule. The rule text controls.
Every witness who takes the stand must promise to tell the truth before they can testify. This promise can be a formal oath or a simple affirmation. Either way, the goal is the same: to remind the witness that they have a serious duty to be honest.
The court doesn't require one exact set of words. What matters is that the process makes the witness understand they must tell the truth and feel a real sense of responsibility about it. This might mean swearing an oath in the traditional way, or it might mean affirming honestly without religious language, depending on what fits the witness's beliefs.
The point of this rule is to make sure every person who testifies understands, before they say a word, that they are expected to be truthful and that there are consequences for lying under oath.
