11 Then each of them was given a white robe, and they were told to wait a little longer, until the full number of their fellow servants, their brothers and sisters,a were killed just as they had been.

Read Revelation 6:11 Using Other Translations

And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
Then they were each given a white robe and told to rest a little longer, until the number of their fellow servants and their brothersshould be complete, who were to be killed as they themselves had been.
Then a white robe was given to each of them. And they were told to rest a little longer until the full number of their brothers and sisters —their fellow servants of Jesus who were to be martyred—had joined them.