Zechariah 6:8

8. The greatest enemy of the Jews were the Babylonians, or their successors, the Persians; while their power remained intact there was little hope for a complete restoration. In the first and second visions the prophet had been informed that judgment was about to fall upon that nation; here he is assured once more that the day of judgment is at hand. All the chariots are messengers of judgment, but only the one going toward the north is singled out for further comment.

Have quieted my spirit A prophetic perfect; the act is still future, but it is so certain that the prophet may speak of it as already accomplished. The spirit is the spirit of wrath (Ecclesiastes 10:4), which they are about to quiet, that is, to pacify, by the execution of the judgment (Ezekiel 5:13; Ezekiel 16:42).