The two witnesses can be found in Revelation chapter 11.
The two prophets appear in the end times and are given a three and a half year ministry
to preach God's word whereby they are supernaturally enabled to breathe fire out of their mouths
to devour their adversaries or anyone who desires to hurt them.
Now although their identity isn't explicitly mentioned in the book of Revelation we can
safely surmise who they are based upon some clues.
Verse 6 says that they have power to shut heaven that it rain not in the days of their
ministry.
Alluding to the fact that it could potentially be Elijah who also shut the heavens that it
rain not for three and a half years during his ministry.
Malachi chapter 4 also tells us that Elijah shall be sent before that great and notable
day of the Lord.
Secondly is that they have power to turn the water into blood and to smite the earth with
all plagues as often as they will.
Suggesting that it's referring to Moses since he also turned water into blood and smote
Egypt with all plagues as often as he would.
And lastly when Jesus Christ was transfigured in Matthew chapter 17 the two prophets who
were on the mount with him were Elijah and Moses.
Link in the description for more.