A.T. Robertson Commentary Revelation 19:8

"And it was given unto her that she should array herself in fine linen, bright [and] pure: for the fine linen is the righteous acts of the saints." — Revelation 19:8 (ASV)

That she should array herself (ινα περιβαλητα). Sub-final object clause subject of εδοθη (was given to her) with ινα and the second aorist middle (direct) of περιβαλλω to fling around. This bridal dress is a gift from Christ. This form, εδοθη (it was given), occurs some 20 times in this book.

In fine linen, bright and pure (βυσσινον λαμπρον καθαρον). See 19:14 for the same raiment on those accompanying "The Word of God" and for the seven angels in 15:6. See by contrast the garments of the harlot (17:4; 18:16). For βυσσινον see 18:16.

The righteous acts of the saints (τα δικαιωματα των αγιων). This is the explanation (γαρ) of the bridal dress and explains why there is work for the Bride as well as for Christ (Php 2:12f.). See 15:4 for δικαιωμα .