How does he nullify it? [If] he pruned [it], or trimmed [it], [or] he took a stick from it or a twig —- even a leaf, it is nullified. [If] he shaved chips from it for its own needs, it remains prohibited; not for its own needs, it becomes permitted.

R’ Yishmael says: Three stones, one next to the other, [lying] next to a Marculis, are prohibited, but two are permitted. But the Sages say: Those which appear to be with it are prohibited, but those which do not appear to be with it are permitted.