What is the meaning of al-Tirmidhi's statement: "Hasan for other reasons"? I ask for clarification of this technical term.

The questioner: His EminenceThe Shaykh- May Allah preserve you - What is the meaning of al-Tirmidhi's statement: "Hasan for other reasons"? I ask for clarification of this technical term, and may Allah reward you with good.

The Shaykh: Among the things scholars have observed, and their followers observe with knowledge, is that al-Tirmidhi has technical terms in his book that he used exclusively, unlike other famous scholars. Sometimes he says of a hadith: "A hasan, strange hadith," as you heard, and sometimes he does not use the word "strange," but rather says: "A hasan hadith." The difference is that by the first expression, "hasan, strange," he means "hasan in itself," and by the second expression, "hasan hadith," he means "for other reasons." This is his technical usage. He mentioned the second term at the end of his "Sunan," in the book called the Book of 'Ilal (Defects), saying what means: "Every hadith in which I said 'hasan hadith,' I mean a hadith that came through multiple chains, none of which contains an accused narrator, a narrator whose reports are abandoned, or one who is severely weak." This is the meaning of his words, and this is the hasan hadith that scholars discuss; because it is strengthened by the multiplicity of chains, and they stipulate that it not be severely weak.
As for his first term, "hasan, strange," it cannot be interpreted with the meaning or interpretation of the first term for two reasons. The first is that al-Tirmidhi - may Allah have mercy on him - only explained the hasan hadith and did not explain "hasan, strange." Therefore, it is not permissible to equate the two terms and give them the previous ruling; that is, a hasan hadith for other reasons. This is the first reason, and for a second reason; which is that al-Tirmidhi sometimes, in some hadiths, instead of "hasan, strange" or "hasan hadith," says: "A strange hadith." So what is the meaning of a strange hadith in that case? Strange means: singular, and the intent is that one of those mentioned in the chain of that hadith narrated it alone. So when we return to his first expression, "hasan, strange hadith," we cannot interpret it as meaning the hasan that rose to the level of hasan by coming through multiple chains; because here he said: singular, strange, having no other chains, but rather it is hasan... in its chain. In this case, Imam al-Hafiz al-Tirmidhi - may Allah have mercy on him - indicates that every chain of a hadith in which he said: "hasan, strange"; he means that one of its narrators had a slight deficiency in his precision and memorization of the hadith, so his hadith is hasan in itself; it is not sahih; because in a sahih hadith, the narrator is trustworthy, precise, and a memorizer, whereas in a hasan hadith, the precision and memorization are less than that of the narrator of the sahih hadith. So when he says: "hasan, strange"; he means that the chain is hasan in itself; one of its narrators has a slight weakness in his memorization. This is the intent of al-Tirmidhi's technical term.