'The first resurrection,' mentioned in Revelation 20:5, 6, does not mean a first resurrection, but the essence and primary part of resurrection, which is salvation and eternal life. There is only one resurrection to life. A second does not happen, and is not mentioned anywhere in the Bible.

(References: Apocalypse Explained 6; Apocalypse Revealed 851; Revelation 20:5-6)

6870. 'And this will be the sign to you that I have sent you' means the recognition that the Divine would go forth from Him. This is clear from the meaning of 'the sign' as the corroboration of truth and consequent recognition that it is indeed so; and from the meaning of 'being sent' as going forth, dealt with in 2397, 4710, 6831, so that 'being sent by God' is going forth from the Divine. It is also the Divine going forth from Him, for one who comes forth from the Divine is receptive of the Divine and extends its influence further.