נִשְׁבַּ֤ע יְהוָ֨ה ׀ וְלֹ֥א יִנָּחֵ֗ם אַתָּֽה־כֹהֵ֥ן לְעוֹלָ֑ם עַל־דִּ֝בְרָתִ֗י מַלְכִּי־צֶֽדֶק׃
The LORD hath sworn, and will not repent: 'Thou art a priest for ever After the manner of Melchizedek.'
Read kabbalistic (mystical) interpretation of Psalms 110:4: and classical mystical sources.