4 Which very thing, too, we observe to come from divine authority, that the priest should be chosen in the presence of the people under the eyes of all, and should be approved worthy and suitable by public judgment and testimony; as in the book of Numbers the Lord commanded Moses, saying, “Take Aaron your brother, and Eleazar his son, and place them in the mount, in the presence of all the assembly, and strip Aaron of his garments, and put them upon Eleazar his son; and let Aaron die there, and be added to his people.” God commands a priest to be appointed in the presence of all the assembly; that is, He instructs and shows that the ordination of priests ought not to be solemnized except with the knowledge of the people standing near, that in the presence of the people either the crimes of the wicked may be disclosed, or the merits of the good may be declared, and the ordination, which shall have been examined by the suffrage and judgment of all, may be just and legitimate. And this is subsequently observed, according to divine instruction, in the Acts of the Apostles, when Peter speaks to the people of ordaining an apostle in the place of Judas. “Peter,” it says, “stood up in the midst of the disciples, and the multitude were in one place.” Neither do we observe that this was regarded by the apostles only in the ordinations of bishops and priests, but also in those of deacons, of which matter itself also it is written in their Acts: “And they twelve called together,” it says, “the whole congregation of the disciples, and said to them;” which was done so diligently and carefully, with the calling together of the whole of the people, surely for this reason, that no unworthy person might creep into the ministry of the altar, or to the office of a priest. For that unworthy persons are sometimes ordained, not according to the will of God, but according to human presumption, and that those things which do not come of a legitimate and righteous ordination are displeasing to God, God Himself manifests by Hosea the prophet, saying, “They have set up for themselves a king, but not by me.”
Source: The Epistles of Cyprian (New Advent)