Just be sure to keep an eye on the poop. If the rock was tiny, then he should pass it with no problem. HOwever if you don't see any poo for three days or so, try giving your beardie some unsweetened applesauce with some olive oil in it (not too much). Or you can try unsweetened canned pumpkin. You also may want to
bathe himtwice a day. They take water in through their vents and that may help.
When I have a poop problem with one of my dragons, I feed them one of these things WHILE they are in the
bath. Almost always works. Like a double whammy.
If still no poop, then I recommend taking him to the vet, just in case the rock was not as small as you thought.
Good Luck.