פירוש על חולין 215:16

Mishna: A drop of dairy that falls upon a piece [of meat] - Inside the pot upon one piece [of meat among several] and it the pot is not stirred; it [the pot] will not acquire the taste of the drop, rather only the piece by itself.

A drop of dairy that falls upon a piece of meat, if it gives to the piece a taste - It will be forbidden...if the entire piece is outside of the sauce. This is discussed like it is said in Perek "Gid HaNaase" (Daf צו of Maasechet Chullin). Therefore, from this discussion, the piece [of meat] will nullify the drop [of dairy] and not the remaining pieces because the dairy spreads upon the whole piece, and doesn't spread from the piece to the other pieces. However, [to be finished later]

If it [the drop of dairy] gives taste to a piece [of meat] - that is to say; [if] the piece of meat by itself is not 60 times larger, to nullify the drop, the piece is immediately forbidden. And the remaining pieces in the pot are not discussed by the Tanna of our Mishna. The Gemara argues if the piece returns and makes [all pieces] forbidden or not.