Hebrews 5:6 As he said also in another place, Thou are a priest for ever after the order of Melchisedec. 

‘Thou are a priest for ever after the order of Melchisedec.’ This is the 15th Old Testament prophecy in Hebrews (5:6; Ps. 110:4) and is fulfilled.

‘For ever’ – Christ is an eternal priest, proving there will be eternal worship and eternal duties of the priesthood (5:6; 6:20; 7:3, 17, 21).

‘Order’ [Greek: taxis] order, arrangement, rank, position (5:6, 10; 6:20; 7:11, 17, 21; Luke 1:8; 1Cor. 14:40; Col. 2:5). If He is a priest forever, there can be no priestly succession. As long as men have access to God, there is no need for human mediators between God and man.

‘Melchisedec’ – Melchizedek was a Canaanite and the king of Salem [later named Jerusalem], he was a priest of the most high God and lived in Abraham’s time long before Aaron’s – the high priest of Israel – time (Gen. 14:16-18; Heb. 7:1-10).