Avodah Zarah 3:10-4:1

Avodah Zara 3:10

An idolator can nullify an asheira’s status as an idol by trimming or pruning it, or by taking from it a stick, staff or even a leaf. If he planed the asheira for the tree’s benefit, it remains prohibited but if he did so for his own benefit, it becomes permitted.

Avodah Zara 4:1

Rabbi Yishmael says that if three stones are found next to one another near a statue of Mercury, they are prohibited (because they were placed there as part of the idol’s service) but two are permitted. The Sages say that if even one or two stones are near such a statue, they are prohibited, but if they are not near the statue, then they are permitted.