ISB ~ Revelation 3 v4

soiled their garments:The white garments worn by angels and saints (4:4; 6:11; 7:9; 19:14) symbolize both purity and victory (Dan 11:35; 12:10) and were used in the ancient Church to clad the newly baptized. Some in Sardis had stained their robes by reverting to sinful ways and renewing their friendship with the world.