Is that a literal chain? Like there's that jewelry that has a thing called a prayer box. Or did you mean 'chain' like as in an order of people? Where'd you hear it?
I overheard someone on her cell phone say, "I'm putting you on my prayer chain."
I looked it up. It's a praying network or circle.
When people within the circle have a particular issue they keep each other included, when members find out about other people and issues to pray about they add to it thus extending the 'chain'.
A general prayer chain is a network of individuals who will receive prayer requests and thanksgivings, forward them to the next available person in the network
ah makes sense in the context. thanks!