John Trapp on Psalms 110:4

Verſ. 4. The Lord hath ſworn, &c.] Chriſts Prieſtly Office, as well as his Kingly, is here deſcribed, whereof how many, and how great myſteries there are, ſee Heb. 7. with the Notes. The Church is collected and conſerved not onely by Chriſts Kingly power, but alſo by his Prieſtly mediation.

Thou art a Prieſt] 1. To expiate. 2. To intercede.

After the order of Melchiſedeck] Who whether he were Shem, or ſome other, is not eaſie to determine. Melchiſedeck was a King, and a Prieſt. Chriſt was more, a Prieſt, a Prophet, and a King. Theſe Offices have met double in ſome others; as Melchiſedech, was King and Prieſt, Samuel a Prieſt, and a Prophet; David a King, and a Prophet; but never met all three in any, but in Chriſt alone.