Perhaps the most important question about this Mushaf is the reliability of the narrations about it. The other issues can only be addressed after the determination of credibility of the narrations. Therefore, we must proceed with this questions first.
Methods of determining the Soundness of Narrations
There are a number of ways to understand the soundness of narrations. Of these, three are the most important:
1st: Examining the (credibility and lives of the) men mentioned in the chain of narrators of a hadith.1 If the men are considered to be reliable (i.e. pious and honest at the time of the narration) then the hadith is reliable.
2nd: There are indications other than the chain of narration that sometimes, even though there are multiple chains of narration; the occasion arises that all the narrators possess the necessary qualifications (of piety), but a single narrator in the chain didn't apply that hadith in theory or practice. The scholars consider such a hadith to be weak, otherwise, they wouldn't have disregarded it. Likewise, there are hadith which are not altogether sound, but there are indications that reliable scholars accepted and applied the subject, thus it is considered to be a credible hadith. In such a situation, the narration is considered authentic (وثق) but not well-documented (ثقة).
3rd: Believability and lack of discrepancy between the legislative, doctrinal and historical hadith. Regarding the first type, that is to say, jurisprudential hadith, it is sufficient for the hadith to have a sound chain of narrators. However, regarding the other two, the acceptance of and consensus of opinion between scholars is sufficient (to prove a hadith's reliability).
If you substitute the latter method (believability and consensus of opinion) for the former (multiplicity of chains of narration), then in any case, the proof of credibility of a hadith is one's belief in its credibility without needing to examine who the narrators in the chain are.
Mushhaf Fatimah and the ways of determining the soundness and credibility of narrations
Lo and behold, the moment has come to answer the questions raised so far. The narrations concerning Mushaf Fatimah are sound and reliable by any of the three methods we have noted. If we want to use the third method, every single Shi'a scholar has acknowledged the authenticity of the narrations concerning this Mushaf, and we haven't found a single dissenting scholar (in this regard). This matter strengthens the determination of authenticity using the second method (multiplicity of chains). We should mention that some have said, “Is it possible that Jibra'il(a.s) would descend unto Lady Fatimah(a.s) and impart matters to her, and that 'Ali(a.s) could hear this and write it down?” Others say, “But 'Ali(a.s) is superior in virtues to Fatimah(a.s); he(a.s) seems worthy of such a revelation.”
We will answer these reproaches. For the time being, it suffices to quote 'Allamah Muhsin Amin who said, “it is neither improbable nor is there room for doubt to believe that Jibra'il(a.s) would speak to Zahra(a.s) and that 'Ali(a.s) could hear it. It's recorded in a book by the name of Mushaf Fatimah. What's more, the reliable companions of the Imams(a.s) have narrated such a thing. To those who doubt this, or think it to be improbable, or who think it to be exaggerated or lacking impartiality, I say, 'Do you doubt the power of Allah the most high? Is Zahra(a.s)2, who is of the very essence of the Prophet(s.a.w) not worthy of this grace? Do you doubt the soundness of a narration despite the fact that they were uttered from the very Imams of guidance who were the issue of this noble lady and are totally reliable? Given the fact that this same honor was bestowed on Aasif bin Barkhiyaa and also Sulaymaan(a.s), and they certainly not more dear to Allah than the family of Mohammad(a.s)!3
The reliability of the hadith concerning the Mushaf Fatimah can also be demonstrated by the first method. For example, Kulayni in Al-Kafi considered the hadith and narrations about this book to be acceptable (صحيح).4 In one of these hadiths, Imam al-Sadiq(a.s) says, “Fatimah(a.s) lasted 75 days after the departure of the Prophet of Allah(s.a.w). Because of her father's (death), she suffered a profound sadness. Jibra'il(a.s) alighted to her in order to abate her grieving and to give her something pleasing. He informed her about her father's (state in heaven) and his (exalted) rank and told her what would happen to her descendents. 'Ali(a.s) recorded all this (information), and this is Mushaf Fatimah.5