is more similar to the issue of the sa' from the orchard, and it is closer to it; the rationale we mentioned regarding it holds true here, so it is not valid. And Allah knows best.

Section: If one excludes a specific palm tree or a specific tree, it is permissible. We do not know of any disagreement regarding this; this is because the excluded item is known, and it does not lead to ignorance (jahala) regarding the remainder. If one excludes a non-specific tree, it is not permissible, because the exclusion is unknown, and thus both the sold item and the excluded item become unknown. It has been narrated from Ibn Umar that he sold his fruit for four thousand and excluded the servants' food. This is interpreted as meaning he excluded specific palm trees equivalent to the amount of the servants' food; because if it were interpreted as otherwise, it would contradict the Prophet's (may Allah bless him and grant him peace) prohibition of thunya (exclusion) unless it is known. Furthermore, when the excluded item is unknown, it follows that the remainder after it is also unknown, so its sale is not valid, just as if one said: "I sold you the servants' food from this fruit."

Section: If one excludes a known part from a heap (subra) or an orchard as an undivided share (musha'), such as a third, a fourth, or parts, such as two-sevenths or three-eighths, the sale and the exclusion are valid. Our companions mentioned this, and it is the school of al-Shafi'i. Abu Bakr and Ibn Abi Musa said: It is not permissible. Our evidence is that it does not lead to ignorance of the excluded item nor of the remainder, so it is valid, just as if one bought a specific tree. This is because the meaning of "I sold you this heap except for its third" is: "I sold you two-thirds of it." And his saying "except for its fourth" means: "I sold you three-quarters of it." If one sells an animal and excludes its third, it is permissible, and it means: "I sold you two-thirds of it." Judge Abu Ya'la prohibited this by analogy to the exclusion of fat. That is not correct, because fat is unknown and cannot be sold individually, whereas this (the third) is known and can be sold individually, so its exclusion is valid, like a specific tree. Analogizing a known item to an unknown one in terms of corruption is not correct. Consequently, they become partners in it: the buyer owns two-thirds and the seller owns one-third.