How to play against the b4 najdorf

So this guy played b4 after I played a6:
en.lichess.org/WIrEZ7yF/black#11
I don't really know what this move is. Does anybody play this more often or know about this opening so I know what to do the next time I face this weirdly looking move.

If white can play 6 h3 or 6 a3, then why not 6 b4?
Your reaction 6...g6 is quite logical, though you could also have played 6...Qc7 or 6...Qb6.
I find his 7 h3 even more strange. One reaction to 6 h3 is 6...g6, because h3 is quite useless against ...g6.
I think you did well and you quickly gained an advantage.

I hope you don't get this wrong, but if you don't know how to react on 6.b4? you have no idea of najdorf. The move a6 is not only for the threat b5-b4&Nxe4, it is also "just" a defensive move to protect the square b5 (e.g. after you play e6/e5 the move Bb5+ or Nb5 is not possible)
So the easiest way to contuniue the najdorf (g6 is fine, but you wanted to play a good najdrof, not a good dragon), contunue with e6/d6/Be7/0-0 and Nc6 if you play so against Be2- the shevengingen, or e5 and then Nc6/Be6 and try a fast e5 if you prefer the d6/e5 structure (like in 6.Be3 e5)

@ToLazyToGetAName
6...e6 does not look like a refutation.
6...e5 makes more sense.
Even so one of the possible points of the weird 6 b4 is that he can play b5 after ...Nc6 and after ...axb5 Ndxb5, what the Najdorf was designed to prevent. also ...Nbd7 and ...Nc5 is prevented by the weird 6 b4.
So I think 6...g6, 6...Qc7 or 6...Qb6 are possibilities to exploit the weaknesses 6 b4 has created.

Yeah, I agree what @ToLazyToGetAName is saying. But since he played b4 I figured I will try to play against his weak a1/h8 diagonal and therefore place my bishop on g7 as @tpr also pointed out. I'm not really a fan of playing e5 so quickly since I always have the feeling that my d6 pawn will get and will stay extremely weak. I just started playing this crazy najdorf a while back, so I still don't really know the best breaks and way to attack in the middlegame. Could you guys give me some hints on that or refer to a couple of books. Thanks in regard.

chess24-videos by niclas huschenbeth on the najdorf
ftacnik- GM repertoires 6 (although he has some mistakes)
or "the sharpest sicilian"

*trp: I do agree that e5 or g6 are both stronger than e6. Still e6 gives you an advantage and if the OP is playing e6 on 6.Be2 he is familiar with the structures and just returns to his average positions with the white move b4 included. And as for your opinion (since you dared to correct me) b5 is not a threat since you just play Nxd4 and continue developing. And since you are not playing Nd7-c5, but Nc6 all other issues are gone. You just get a sheveningen and if you don't know what it is, look it up before teaching others how to play it

nobody play that
white can play 8 other much better and viable moves

@ToLazyToGetAName This is a discussion forum, there is no need to be condescending. I am not an international master. At least I know how to spell Scheveningen. Robert Fischer himself approved of 6...g6 as a response to his own 6 h3.
@Calanthe playing ...e5 if possible is the essence of the Najdorf: Miguel Najdorf conceived it as an improvement over the Boleslavsky 5...e5 which leaves a hole at d5. With 5...a6 black blocks the access to that hole via Ndb5. The hole is still there, but white cannot get to it. Kasparov has won many games with black that way.
@currypanang Sure 6 Bg5, 6 Be3, 6 Be2, 6 Bc4, 6 h3, 6 g3, 6 a3, 6 f4, 6 f3, 6 a4 all look better than 6 b4. The question posed here is how to refute 6 b4.

How to refute it? It looks like you did!

@Keru Yeah, somehow. But I didn't know the reason behind that move and why white should play that.

Thanks to all who commented and helped me on the Najdorf. I'll look at it in more detail.