The Methodology of Imam al-Nasa'i, and Sunan al-Kubra vs. Al-Mujtaba
The questioner asks about the condition of al-Nasa'i in his Sunan — and secondly: why has the book not received much service [in the form of explanations and the like]?
Al-Nasa'i has no explicitly stated condition — meaning al-Nasa'i did not declare: "My condition for this book is such-and-such." But one can infer the condition of al-Nasa'i from his methodology in the book. The Sunan of al-Nasa'i is among the most beneficial and finest of books.
Whoever has interest in the science of hadith defects ('ilal), the science of narrators (rijal), the science of chains of transmission (asanid), authentication, and weakening — he can never do without the Sunan of al-Nasa'i. Because Imam al-Nasa'i is one of the senior imams in this science. His authentication carries weight and standing and station.
The Sunan al-Kubra is printed and in circulation, with various print editions. And in truth, the Kubra has been given great attention — the Egyptian edition and the Qatari edition — all these editions have been given attention in the precision of the text, the takhrij, and the comparison with manuscripts — something unprecedented before. And in terms of commentary: yes — it has not benefited from extensive explanation, though it does have annotations — and there is an explanation now being released gradually, one volume after another, which I see is quite expansive on this book. But this book is among the important works. Every student of knowledge ought to pay attention to it, focus on this book, extract its defects, and memorise them. Extract the opinions of al-Nasa'i from this book.
The condition of al-Nasa'i (may Allah have mercy on him) — as understood from his methodology — is a rigorous condition. But as I said, al-Nasa'i did not mention a stated condition. Rather, this is understood from his compilation — a rigorous and significant condition. Until some scholars said that al-Nasa'i's condition is more rigorous than the condition of Muslim. This may be looked at, but what remains is that the Sunan of al-Nasa'i is among the finest and most beneficial of books. And if a hadith is found defective in his Sunan, rarely does it escape a defect.
Al-Mujtaba and the Error of Attributing Its Selection to al-Nasa'i
His published book Al-Mujtaba is known as the Sunan al-Sughra. It is not from the composition of al-Nasa'i himself, as many imagine — as one sees in the annotations of some books. For instance, in the book comparing hadiths against the two Sahihs — every hadith that al-Nasa'i is silent on, the annotator comments: "Sound, because al-Nasa'i mentioned it in Al-Mujtaba." This is wrong — this is a pure mistake.
Al-Nasa'i (may Allah have mercy on him) did not say that this is sound, nor did he compile Al-Mujtaba himself at all. Rather, the one who compiled it from [al-Nasa'i's work] was Imam Ibn al-Sunni — and not al-Nasa'i himself. There is a difference between the two works. Accordingly, it is not to be attributed to al-Nasa'i that he authenticated the hadiths of Al-Mujtaba. The hadiths of Al-Mujtaba include the sound and include the weak.
Al-Nasa'i (may Allah have mercy on him) did not place a stated condition for it. The well-known story that some scholars of hadith methodology mentioned — that al-Nasa'i compiled [Al-Mujtaba] for some rulers, selected it from the Sunan al-Kubra, and that this represented what was sound from the Sunan al-Kubra — this story is not correct. Al-Nasa'i (may Allah have mercy on him) did not select [it] from the Sunan al-Kubra.