Acts 3:12
And when Peter saw it, he answered unto the people, Ye men of Israel, why marvel ye at this? or why look ye so earnestly on us, as though by our own power or holiness we had made this man to walk? And when Peter saw it, he answered unto the people, Ye men of Israel, why marvel ye at this? or why look ye so earnestly on us, as though by our own power or holiness we had made this man to walk?
The question was asked just after the sudden healing of a man lame from birth, who entered the temple walking and leaping and praising God to the amazement of the people. The priests had expected miracles to end with Jesus' death, and the people wondered where His followers had obtained power to work miracles after His crucifixion. Peter understood their perplexity as he answered them.
He would not let them marvel at the apostles or look earnestly on them with awe. He denied that he and John had made the man walk by their own power or holiness or worthiness. Their words and works after the resurrection were given under the power of the Holy Spirit and represented their Teacher Jesus, pointing to the risen Lord rather than to themselves.
The healing was given in the name and merits of Jesus Christ of Nazareth, through faith in Him. The disciples depended humbly on Christ's strength and righteousness and did not regard their own power or worthiness as its source. The miracle was done by power Jesus imparted to His followers after ascending to heaven. They directed all attention, honor and praise away from themselves toward Him.
The Jesus to whom Peter pointed is the one the God of Abraham and of Isaac and of Jacob glorified and raised from the dead and exalted. Peter used the people's wonder as occasion to proclaim Him. He confronted them with their rejection and crucifixion and murder of Him. This healing and proclamation fulfilled what God had foretold through the prophets, that Christ would suffer.