7 But it is manifest where and by whom remission of sins can be given; to wit, that which is given in baptism. For first of all the Lord gave that power to Peter, upon whom He built the Church, and whence He appointed and showed the source of unity— the power, namely, that whatsoever he loosed on earth should be loosed in heaven. And after the resurrection, also, He speaks to the apostles, saying, “As the Father has sent me, even so I send you. And when He had said this, He breathed on them, and says, unto them, Receive the Holy Ghost: whosesoever sins you remit, they are remitted unto them; and whosesoever sins you retain, they are retained.” Whence we perceive that only they who are set over the Church and established in the Gospel law, and in the ordinance of the Lord, are allowed to baptize and to give remission of sins; but that without, nothing can either be bound or loosed, where there is none who can either bind or loose anything.
Source: The Epistles of Cyprian (New Advent)