“DON’T you know that the laying on of hands after baptism and then the invocation of the Holy Spirit is a custom of the Churches? Do you demand Scripture proof? You may find it in the Acts of the Apostles. And even if it did not rest on the authority of Scripture the consensus of the whole world in this respect would have the force of a command. For many other observances of the Churches, which are due to tradition, have acquired the authority of the written law.”
~St. Jerome: Dialogue Against the Luciferians, Ch. 8.