Najdorf who or what is it?
The Najdorf variation of the Sicilian Defense, are there any books on it?
Try googling it. I'd imagine there'd be tonnes of books, but there are probably videos on youtube, or here on chess.com
You could get an old book on all Sicilians The Sicilian labyrinth by lev polugaevsky in two small volumes
Well annotated games, deal with ideas, like pawn structure sacrifices etc. with a lot of move order tricks
It is quite possible that your opponent won' stay in the najdorf but could transpose away.
Whatshisface did a great video on the Najdorf some time back but I forget which site it was on and anyway I think it was deleted. I hope you find this answer helpful.
The best book is probably this:
...but it's probably completely inappropriate for you, so possibly this:
...or even this(which is not just about the Najdorf):
There's at least ten different books on Amazon. Also, there's a chessbase DVD on the subject.
If you'd like to go over some PGN's this is a good site: http://www.chessgames.com/perl/chessplayer?pid=21930
Also check out Fischer on the site as well. He played the Najdorf.
Try: "Play the Najdorf Scheveningen Style", by John Emms