Zechariah 6:13

6:13 Indeed, he will build the temple of the Lord, and he will be clothed in splendor, sitting as king on his throne. Moreover, there will be a priest ¹  with him on his throne and they will see eye to eye on everything.

Zechariah 12:8

12:8 On that day the Lord himself will defend the inhabitants of Jerusalem, so that the weakest among them will be like mighty David, and the dynasty of David will be like God, like the angel of the Lord before them. ² 

[6:13]  ¹ sn The priest here in the immediate context is Joshua but the fuller and more distant allusion is to the Messiah, a ruling priest. The notion of the ruler as a priest-king was already apparent in David and his successors (Pss 2:2, 6-8; 110:2, 4), and it finds mature expression in David’s greater Son, Jesus Christ, who will combine both offices in his kingship (Heb 5:1-10; 7:1-25).

[12:8]  ² sn The statement the dynasty of David will be like God is hyperbole to show the remarkable enhancements that will accompany the inauguration of the millennial age.