Jesus gave Peter the keys of the kingdom of heaven.

"And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven." - Matthew 16:19 KJV

When Peter preached to the Jews the gospel of Jesus, they were pricked in their heart and asked, “What shall we do?” Peter then shared with them the keys of the kingdom of heaven.

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost." - Acts 2:38 KJV

It was when Peter understood who Jesus is, that Jesus gave Peter the keys of heaven. On the day of Pentecost, Peter used this revelation from God to preach the gospel message of the name of Jesus that saves the world.

"Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved." - Acts 4:12 KJV