is the a rat snake ??
It looks like a Rat Snake to me, however my understanding is that the distribution of these is quite limited in UAE and as such I'm more inclined to say that it is a Wadi Racer. The species look quite similar, however I'm pretty sure that Rat Snake have only been found on islands off the coast of the UAE. Did you manage to get a close up of the head by any chance? Hopefully someone will have further clarification on the species.
It is surely a WADI RACER. Best wishes,
Dr. Reza Khan