It is stated in *Mukhtasar Minhaj al-Qasidin* as follows:
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The questioner : I had mentioned before asking, if Allah wills, that it is not permissible to combine this and that, the date pits and the dates. So I was asked: Where did you bring that from? From a book that our brother 'Ali has authenticated, may Allah reward him with good.
The Shaykh : Yes.
The questioner : In *Mukhtasar Minhaj al-Qasidin*, it says: And among that is not blowing on hot food, and not combining dates and pits in one dish, and not combining them in one's palm, but rather one places them from one's mouth on the back of one's palm and then throws them away. And likewise, anything with bones or pits, meaning dregs, one does not combine this with that. So our brother 'Ali is silent about it, and for that reason I asked you the question you mentioned.
The Shaykh : And I am like our brother 'Ali. (laughs)The Shaykh : (may Allah have mercy on him) and I sought it, and I say: I do not know anything in the Sunnah regarding the prohibition of combining the aforementioned items. But this is a matter of taste, meaning that even if there were something in the Sunnah that is hidden from us, this would be in the category of what is said in some hadiths: this is a matter of guidance, and not a legal ruling such that whoever does it would be sinful.
The questioner : In Sahih Muslim...
The Shaykh : A moment, let us listen. Are you done?
The questioner : Yes, Professor.
The Shaykh : Are you done?
The questioner : I asked our professor, may Allah reward you with good, if there is any hadith or evidence for that, may Allah reward you with good.
The Shaykh : The issue of combining the pits and the fruit from which they came, these pits, I do not know anything about it. Please proceed.
The questioner : I recall, my Shaykh, a hadith in Sahih Muslim regarding the prohibition of placing pits with dates, meaning: after eating, meaning: placing them with the dates or on the dates.
The Shaykh : In Sahih Muslim?
The questioner : That is what I recall.
The Shaykh : I do not recall. Do you have anything?
The questioner: No...
The Shaykh: Ah, okay.
The Shaykh : Yes.
The questioner : In *Mukhtasar Minhaj al-Qasidin*, it says: And among that is not blowing on hot food, and not combining dates and pits in one dish, and not combining them in one's palm, but rather one places them from one's mouth on the back of one's palm and then throws them away. And likewise, anything with bones or pits, meaning dregs, one does not combine this with that. So our brother 'Ali is silent about it, and for that reason I asked you the question you mentioned.
The Shaykh : And I am like our brother 'Ali. (laughs)The Shaykh : (may Allah have mercy on him) and I sought it, and I say: I do not know anything in the Sunnah regarding the prohibition of combining the aforementioned items. But this is a matter of taste, meaning that even if there were something in the Sunnah that is hidden from us, this would be in the category of what is said in some hadiths: this is a matter of guidance, and not a legal ruling such that whoever does it would be sinful.
The questioner : In Sahih Muslim...
The Shaykh : A moment, let us listen. Are you done?
The questioner : Yes, Professor.
The Shaykh : Are you done?
The questioner : I asked our professor, may Allah reward you with good, if there is any hadith or evidence for that, may Allah reward you with good.
The Shaykh : The issue of combining the pits and the fruit from which they came, these pits, I do not know anything about it. Please proceed.
The questioner : I recall, my Shaykh, a hadith in Sahih Muslim regarding the prohibition of placing pits with dates, meaning: after eating, meaning: placing them with the dates or on the dates.
The Shaykh : In Sahih Muslim?
The questioner : That is what I recall.
The Shaykh : I do not recall. Do you have anything?
The questioner: No...
The Shaykh: Ah, okay.
Source
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The Arabic text is copied verbatim from the original source, without any edits.