Imam `Al? ibn al-Husayn is reported to have written down many epistles the most famous of which are Ris?lat al-Huq?q (The Treatise on Rights) and al-Sah?fah al-Sajj?diyyah commonly known as “The Psalms of Islam.” It has been narrated that Ab?-Hamzah al-Tham?liy said, “As I recited an epistle that comprised the words of (Imam) `Al? ibn al-Husayn on asceticism, I copied it. I then showed my copy to `Al? ibn al-Husayn who confirmed and corrected it.”
It is probable that Ab?-Hamzah al-Tham?liy had read a part of the al-Sah?fah al-K?milah al-Sajj?diyyah because this epistle comprises many topics besides asceticism. It is also probable that the book was a part of Imam `Al? ibn Ab?-T?lib’s Book since Imam al-Sajj?d had that book with him. It has been narration, in this respect, that when he was asked about an issue, he answered that in the Book of `Al?, it is written... etc.
Shaykh al-Kulayniy, too, has narrated on the authority of Imam Ja`far al-S?diq that whenever Imam `Al? ibn al-Husayn read the Book of Imam `Al?, he would say, “Who can do all this?” He would then act upon it.
In addition, Imam Muhammad al-B?qir, Zayd ibn `Al? (the martyr), and al-Husayn al-Asghar are reported to have narrated from their father an epistle on the rulings of the ritual Hajj.
Imam Muhammad al-B?qir and Zayd ibn `Al?, sons of Imam `Al? ibn al-Husayn, are also widely known as having cared for the documentation of the religious knowledge. Shaykh Ahmad Muhammad Sh?kir, the editor of the book of Maf?th Kun?z al-Sunnah, has considered the book of Zayd ibn `Al? entitled al-Majm?`—on the assumption that the book is truly ascribed to him—the oldest among the books of the ancient master scholars.
Mr. Muhammad `Ajj?j al-Khat?b says,
“In view of that, the book of al-Majm?` is considered the most important historical document proving that the compilation and writing down of books began at the beginning of the second century (of Hijrah). This fact has been concluded through our presentation of many books and compilations without putting our hand on any material model representing the foremost of these books except for M?lik ibn Anas’s al-Muwatta' which was accomplished before the middle of the second century. Accordingly, the book of al-Majm?` was written down thirty years before al-Muwatta'. Obviously, the book of al-Majm?` comprised inseparably the two collections of the Muslim jurisprudence and the Had?th.”
From the book of Tamh?d(un) Li-T?r?kh al-Falsafah al-Isl?miyyah, Asad Haydar quotes the following:
“Zayd ibn `Al? wrote a jurisprudential record, which has been discovered among the ancient manuscripts in the Biblioteca Ambrosiana, Milan; section of the Southern Arab lands. This manuscript is considered the most ancient collection on the Muslim jurisprudence. In any case, this book should be taken into consideration as regards the compilation of the Muslim jurisprudence.”
The books has been published under the title of Musnad al-Im?m Zayd ibn `Al?.
Nevertheless, since the time of the Holy Prophet, many records were written down and these are surely more ancient than the collection of Zayd ibn `Al?. Moreover, the material model of the Islamic records belongs to the first century (of Hijrah) as represented by Ris?lat al-Huq?q and al-Sah?fah al-K?milah al-Sajj?diyyah, which were put in written forms by Ab?-Hamzah al-Tham?liy and others. These two books are two lively material models that are still surviving.
It is worth mentioning that the books of Imam `Al? ibn al-Husayn, in their major significance, betook themselves a new trend in the Muslims’ documented culture and opened new fields, which are still huge in the heritage of the Muslims. These fields are the Du`?' (Supplication) and the Huq?q (Rights). As a matter of fact, these two fields are considered the most important and ancient culture ever known by the Muslims, because they treated the two most necessary matters needed by the Muslim community during the lifetime of Imam `Al? ibn al-Husayn after the Islamic ethics and the individual and social rights had been about to be wiped out during the reigns of Yaz?d ibn Mu`?wiyah and the rulers who followed him. As a result, the recordation of the treatments of these issues stood for the documentation of the diseases and remedies of that period of the Islamic history, as well as the history of an important stage of the Islamic legislation and fresh Islamic knowledges.
On the assumption that the book of al-Majm?` is truly ascribed to Zayd ibn `Al?, the records of Imam `Al? ibn al-Husayn confirm the authenticity of the books of Imam Muhammad al-B?qir and Zayd ibn `Al?, for their books comprised materials that they had received on the authority of their father from their ancestors.
It has been also narrated on the authority of Ibn al-Safw?n that Zayd ibn `Al? wrote another book entitled al-Qillah wa’l-Jam?`ah upon which he depended in disputing against his rivals.
In the introduction of his revision of the book of al-Safwah that is ascribed to Zayd ibn `Al?, N?ji Hasan writes down that more than ten epistles on various topics, such as theology, Tafs?r, Muslim jurisprudence, and narrations are ascribed to Zayd ibn `Al?.
Sayyid al-Mu’ayyidiy al-Hasaniy has also listed some titles of the books written by Zayd ibn `Al?, yet I have not been acquainted with any further information about these books.
Mr. `Abd al-Hal?m al-Jundiy has also quoted that `Amr ibn Abi’l-Miqd?m compiled a comprehensive reference book on the Muslim jurisprudence that he had reported from Imam `Al? ibn al-Husayn Zayn al-`?bid?n.
Recently, Sayyid Muhammad Jaw?d al-Jal?liy has revised the book of Ghar?b al-Qur'?n that is ascribed to Zayd ibn `Al?. The book has been published by the Islamic Propagation Organization - Iran.
It is now noticeable that the Holy Imams of the Ahl al-Bayt gave considerable attention to the process of recording and reporting the religious knowledge in general and the heritage of the Holy Prophet in particular. In addition, they themselves used to record the Had?th, instruct their sons to do it, and encourage their disciples on writing down. The age of Imam `Al? ibn al-Husayn should be considered exclusively; it was the most critical age by which the Scholars of the Ahl al-Bayt passed since it followed the Incident of al-Taff (the martyrdom of Imam al-Husayn). By virtue of the documentation of the Holy Prophet’s heritage, precious books during that age of the Islamic history came to light. This was in fact one of the miracles in the history of the Muslim culture.
 These two famous epistles have been frequently published, and many explanations have been written for them. They have been also translated into many languages.
 Shaykh al-Kulayniy: al-K?f? 8:14, 17; Shaykh al-T?siy: al-Fihrist 68 No. 138.
 Shaykh al-Kulayniy: al-K?f? 7:40 H. 1, 2; Shaykh al-Sad?q: Man-l?-Yahduruhu’l-Faq?h 4:204 H. 5473; Ma`?n? al-Akhb?r 217 H. 1.
 Shaykh al-Kulayniy: al-K?f? 8:163 H. 172.
 This epistle has been published (in its origin language) by al-Fur?t Press—Baghdad with an introduction by Sayyid Hibat al-D?n al-Shahrist?niy, yet it has been ascribed to Zayd ibn `Al? rather than his father.
 Maf?th Kun?z al-Sunnah, edited by Shaykh Ahmad Muhammad Sh?kir 4.
 Muhammad `Ajj?j al-Khat?b: al-Sunnah qabl al-Tadw?n 371.
 Asad Haydar: al-Im?m al-S?diq wa’l-Madh?hib al-Arba`ah 1:550 as quoted from Mustaf? `Abd al-Razz?q: Tamh?d(un) Li-T?r?kh al-Falsafah al-Isl?miyyah 200.
 Details of this fact have been previously cited in this book. Shaykh al-Kulayniy, in al-K?f? 2: 600, has recorded a narration on the authority of Imam Ja`far al-S?diq explaining this issue.
 Sayyid Majd al-D?n al-Mu’ayyidiy al-Hasaniy: al-Tuhaf Sharh al-Zulaf 30; N?j? Hasan: Thawrat Zayd ibn `Al? 35.
 N?ji Hasan: al-Safwah 9.
 Sayyid Majd al-D?n al-Mu’ayyidiy al-Hasaniy: al-Tuhaf Sharh al-Zulaf 30.
 `Abd al-Hal?m al-Jundiy: al-Im?m Ja`far al-S?diq 202.