That the old priesthood should cease, and a new priest should come, who should be for ever
In the cixth Psalm: “Before the morning star I begot you. The Lord has sworn, and He will not repent, You are a priest for ever, after the order of Melchizedek.” Also in the first book of Kings, God says to the priest Eli: “And I will raise up to me a faithful priest, who shall do all things which are in my heart: and I will build him a sure house; and he shall pass in the presence of my anointed ones for all days. And it shall be, whosoever shall remain in your house, shall come to worship for an obolus of money, and for one loaf of bread.”
Source: The Treatises of Cyprian (New Advent)