And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth. These are the two olive trees, and the two candlesticks standing before the God of the earth. (Revelation 11:3-4)
The passage above does not clearly identify who the two witnesses are. However, the following verse was a promise given to the apostle John as he wrote the book of Revelation.
And he said unto me, Thou must prophesy again before many peoples, and nations, and tongues, and kings. (Revelation 10:11)
Tradition states that John was exiled to Patmos by the Emperor Domitian around 95 AD and then returned to his home in Ephesus 18 months later. John was probably in his 90s at this point, and there is no Biblical or historical evidence that John prophesied “before many peoples, and nations, and tongues, and kings” after he left Patmos. However, the two witnesses will do exactly that. Since this promise must be fulfilled, it is very possible that John is one of the two witnesses.
God made a similar promise to the prophet Daniel:
But go thou thy way till the end be: for thou shalt rest, and stand in thy lot at the end of the days. (Daniel 12:13)
The Hebrew word translated lot can also mean portion, or “thing assigned by casting lots”. So it appears that Daniel will rest and then stand to fulfill his assignment in the “end of the days”. It is possible that Daniel is the second witness.
The ministry of these two witnesses is described in Revelation 11:5-13.