פירוש על קידושין 105:1

So now we have a dispute about whether there is a dispute. Those rabbis sure love their disputes!

Abaye is now going to quote a long baraita that in its totality supports R. Yohanan. The details of this baraita are not relevant for our sugya, but I will still, of course, explain them briefly. The main message of the baraita is that the priests may not exchange one sacrificial gift (meat, fowl or meal-offering) for another.
Priests who receive meal-offerings as part of their portions may not demand to exchange them for sacrificial meat.