The Canons of the Council in Trullo; Often Called The Quinisext Council 14Canon XIV.

Let the canon of our holy God-bearing Fathers be confirmed in this particular also; that a presbyter be not ordained before he is thirty years of age, even if he be a very worthy man, but let him be kept back. For our Lord Jesus Christ was baptized and began to teach when he was thirty. In like manner let no deacon be ordained before he is twenty-five, nor a deaconess before she is forty.