15 Therefore are they before the throne of God, they serve him day and night in his temple. He who sits on the throne will spread his tent over them.
His temple…tabernacle – the entry to the heavenly temple and tabernacle is also described in Rev 11:19, 21:3.
They serve Him day and night – these are the saints from the Great Tribulation who were previously accused before God “day and night” (Revelation 12:10). Now they serve Him day and night.