Zechariah 14:7

At evening time it shall be light - At the close of this awful visitation, there shall be light. The light of the glorious Gospel shall go forth from Jerusalem; and next, from the Roman empire to every part of the earth.

And it shall be one day: it shall be known unto the Lord: not day, and not night; and at the eventide it shall be light - "One" special "day; one," unlike all beside; known unto God, and to Him alone. For God alone knows the day of the consummation of all things, as He saith, "Of that day and that hour knoweth no one, neither the angels in Heaven, nor the Son, (so as to reveal it) but the Father only" Mark 13:32. Neither wholly "day," because overclouded with darkness; nor wholly "night," for the streaks of light burst through the darkness chequered of both; but in "eventide," when all seems ready to sink into the thickest night, "there shall be light." Divine light always breaks in, when all seems darkness; but then the chequered condition of our mortality comes to an end, then comes the morning, which has no evening; the light which has no setting; "perpetual light, brightness infinite;" when "the light of the moon shall be as the light of the sun, and the light of the sun shall be sevenfold" Isaiah 30:26; and "the glory of God doth lighten" Revelation 21:23 the eternal city, "and the Lamb is the light" thereof; and "in Thy light we shall see light" Psalm 36:9. "Christ shall be to us eternal light, a long perpetual day."

14:7 One day - One continued day, no setting of the sun to make it quite night: God will always act in order to the full salvation of his spiritual Jerusalem. Known unto the Lord - The Lord knows when it shall begin, and how, and when it shall end.