Tongue injury

My dog was terribly hurt by groomer who accidentally cut his tongue. Bleeding stopped but part of his tongue on the side is split in two pieces. My vet said that it will heal and surgeon suggested not to suture while it is 1 cm cut. He didnt drink water since yesterday and he seems to be bothered by that. Is he going to get used to it and how it can be fixed ?

Hello!  It sounds as if the surgeon has had a good look at the wound and given it their best judgement.  Indeed, I have seen some absolutely butchered tongues heal - the question is whether bits are likely to get caught in there (but the surgeon has hopefully weighed that up and given you some guidelines on what to feed) and whether pain releif is adequate or whether alternative ways of feeding (tube feeding etc) are needed in the meantime.  If you don't think they've got this right, you do need to go back to your vet and make sure they're fully aware of everything you're seeing;  they will hopefully help to modify the plan if appropriate.