5:18 the day of the Lord. Ultimately, this is the great and terrible “day of the Lord” when He comes in judgment (cf. Is. 2:12; 13:6–13; Obad. 15; Zeph. 1:7, 14). Every Old Testament judgment was also a “day of the Lord,” and anticipated that final day. Joel described it as a day of terrible judgment and destruction (Joel 1:15–20; 2:11), although it would also be accompanied by a redemptive outpouring of God’s Spirit (Joel 2:28–32).
darkness, and not light. The Lord alone has power to make day as dark as night, both literally and figuratively, in judgment (v. 8).