Live tournament ruling

As in he showed the best hand and you mucked and then the dealer showed you his cards?

Only if its an all-in, then you have to show if anybody wants to see it, even if you muck. But if he just bet and you call, Im pretty sure you dont have to show it.

Pretty sure the rule is in place to help stop collusion/ chip dumping.

from my (little) experience if both players are all-in before the river, the cards are on there backs and the hand is run.

not 100% sure about all-ins on the river. The person making the bet should insta flip their hand, or muck it.

if it was just him that bet>you called>he shows>you muck>and then he asks to see your hand, that would be classed as bad etiquette IMO.

At some casinos you dont have to show there are no ruling about having to show your hand when you are all-in, and since it is the ladt aggressor who have to show first the other player will often muck the hand if he have the worst hand he will usually muck, but in reallity anybody can ask to see the cards.

But I would say its just something you dont do.

Not all in. He bets, I call. I don't turn it over and pushed it forward after being shown better pair. Bettor wants to see my hand and dealer flips it over. I don't remember if hand was already in the muck. Grosvenor casino in Coventry

short:I didn't wanted to show what I called with but dealer showed my hand after bettors request.

Bad etiquette by the dealer.

I had a dealer who took my hand from the muck and flipped it over just because he was too curious himself, folded a pair of Kings with four to a flush and big river bet, and he flips my cards over and everyone starts asking how i folded that.. i wanted to slap that dealer, but i chalked it up to a rookie dealer still learning the ropes

If I understand this correctly - yes, it's allowed and yes, it's bad ettiquete (though I think it's fine).