Divine Foundations of Priesthood and Worship
Divine instructions for priests are contained in the prescriptions that define the lawful priesthood of the Church according to Old Testament and New Testament texts. In particular, the document from link txt details that the priesthood is intended for chosen individuals endowed with special rights and responsibilities: they are called to teach, perform sacraments, and bless the people, and they are ordained into service through the laying on of hands accompanied by a prayer in which a special gift of the Holy Spirit is bestowed.
As for the beginning of the ministry, it starts with a proclamation – the sacred beginning of the worship service. As stated in the quote from link txt:
"Ministry begins with a proclamation, and the proclamation is also an entirely special moment of the worship service. The ordinance considers the proclamation a sanctity, to which unordained mouths should not have access. The proclamation – the beginning of the worship service – is always pronounced by the minister."
Thus, according to these accounts, the priestly ministry is founded on divine prescriptions concerning lawful priesthood, which includes teaching, conducting sacraments, and bestowing blessings, while its inception is marked by a special proclamation delivered solely by the minister.
Supporting citation(s):
"Christ's Church, like the Old Testament one, must have a lawful priesthood: Eph. 4, 11; 1 Cor. 12, 28; Heb. 5, 4-5; 7, 12; Isa. 66, 20-21. ... The priestly ministry is instituted through the laying on of hands accompanied by a prayer ..." (source: link txt)
"Ministry begins with a proclamation, and the proclamation is also an entirely special moment of the worship service. The ordinance considers the proclamation a sanctity, to which unordained mouths should not have access. The proclamation – the beginning of the worship service – is always pronounced by the minister." (source: link txt)