People believed healing power rested in the shadow of which disciple?

Peter

Explanation:

People have great faith in the miracle-working of Peter's shadow. People even put their efficacy in the shadow of Peter. But there was doubt that people were healed but it was not sure that Peter's shadow healed them.

People want to believe that there is something in the shadow of Peter. They want to faith in him. People believe that there is some power in Peter so they always try to maintain proximity with peter so some power can pass to them.