A more thorough explanation:

A swift witness is someone who is very enthusiastic and passionate about sharing their testimony or beliefs with others. This term is often used in religious contexts.

For example, a person who goes door-to-door to share their faith with others could be considered a swift witness. They are eager to spread their message and are not afraid to approach strangers to do so.

Another example of a swift witness could be someone who is very vocal about their political beliefs and is always trying to convince others to see things their way. They may attend rallies or protests and use social media to share their views.

Overall, a swift witness is someone who is not afraid to speak up and share their beliefs with others, even if it means facing opposition or criticism.