I heard this story from a missionary, who heard the story from the missionary that experienced this event.
The missionary was serving in a remote area in East Africa, and every Saturday would drive a few hours to a larger town to resupply. The town had an internet café, and he could review and respond to emails from the previous week.
Shortly after arriving he ran into a man who had caused problem for the ministry, but was able to disengage and go to the store and then the internet café. Things took longer than he had hoped, and he started back home at sunset. He could not drive in the bush at night because of the large animals, so he pulled off the gravel road, made a fire, cooked some dinner, then slept in the vehicle. The next morning he made the rest of the drive.
When he returned to the town the next Saturday, he encountered the same man who asked him “Who were those 20 men around your campfire?” “What are you talking about?” the missionary replied. “I was alone.” The man said “My friend and I followed you, to kill you and steal your truck and everything in it. We saw you sitting by a campfire surrounded by 20 men and we left.”
The missionary again explained that he was alone, said a prayer of thanksgiving, and went to the internet café. He found an email received the Saturday before, after he had left town, from his good friend in Mississippi. The friend said their church was having a golf event, with 5 foursomes. Just as they were to start play, the friend had an intense feeling that they needed to pray for the safety of the missionary, made a prayer circle of the 20 golfers, and did so.
Morning in Mississippi is early evening in East Africa.
When the Holy Spirit prompts you to pray for someone, do it. Do not wait. You may not know the specific need or problem, but the Holy Spirit does. (Romans 8:26-27)
A prayer circle is simply a group of believers gathering in intercessory prayer
https://www.christianity.com/wiki/prayer/what-is-the-purpose-of-prayer-circles.html