Institutes of the Christian Religion (1559) - John Calvin
Book 2 - God the Redeemer
Chapter 15 - To Know the purpose for which Christ was sent by the Father and what He conferred upon us, we must look at Him as prophet, king and priest
Sections 6 - Priestly office: reconciliation and intercession
Christ intercedes for us forever, offering a sacrifice -His death - that satisfies God's wrath against our sin. Heb 9:7, 22; Lev 16:2-3
He is our everlasting mediator and intercessor: Ps 110:4; Heb 5:6; 7:15.
He is both priest and sacrifice.
We are now priests with Him - Rev 1:6 - offering acceptable prayer and praise.