A white robe symbolizes the victory of the martyrs and God's complete acceptance.
told to rest: Death is a state of rest (compare John 11:11–12) where martyrs await God's justice.
the full number: Only God knows how many Christians will be killed because of their faith before the end. In his complete authority and power, God will achieve his purposes through his martyred children and will vindicate them at the right time.
brothers: The Greek word adelphoi refers to both male and female members of the same family.