Sharh Usul al-Kafi (Commentary upon the Usul al-kafi), Kitab al-Tawhid, Volumes 3 and 4
Undoubtedly, one of the important and extensive commentaries written on the book al-Kafi belongs to Mulla Sadra. It is mixed with gnosis and philosophy and is, in fact, a religious support for the principles of his philosophy.
He has interpreted and written a commentary on the book of Tawhid (oneness) of Usul al-kafi in 20 chapters and 2 supplements, which generally consists of 133 hadiths (from hadith 211 to hadith 343).
After praising God, Mulla Sadra says in the Introduction of the book:
Since the purpose of the mission of the prophets and messengers and the descent of heavenly books and religious laws is to lead people towards Almighty God and cure their souls from diseases of ignorance, blindness, etc. obviously, any insightful person will learn that traveling this road and being a good servant to God will not be possible without awareness, knowledge, monotheism, and observing piety and purity. Consequently, the most exalted destination and the most supreme of all stations for favorites of God is believing in His Onenes.
The subjects that Mulla Sadra comments on and interprets in the chapters of this book are as follows:
1. Createdness of the world and demonstrating its creator (6 hadiths).
2. The permissibility of interpreting Almighty God as an object (7 hadiths).
3. God cannot be known unless through Himself (3 hadiths).
4. The lowest level of theology (3 hadiths).
5. The object of worship (3 hadiths).
6. Creation and place (8 hadiths).
7. The negation of connection and relatedness to Almighty Truth and God's purity from any kind of relation to and unity with people.
8. Forbidding talking about the quality of the Essence of Almighty Necessary.
9. Rejection of the possibility of seeing Almighty Truth.
10. Forbidding describing Almighty Truth except resorting to what He has described about Himself.
11. Negating body and form to God
12. Attributes of Almighty Truth
13. A supplement to the part on attributes
14. On God's Will, which is among the attributes of His Act, and other attributes of His Acts
15. Createdness of names
16. The meanings of names and their derivations
17. A supplement to chapter 16 including the common names of the Creator and His creatures and the differences between them
18. Interpreting the attribute "Impermeable"
19. Motion and transition
20. Throne of Heaven and the Divine Seat
21. The Spirit
The third and fourth volumes of Sharh usul al-kafi by Mulla Sadra has been published with the edition, research, and Introduction of Mahmud Fadil Yazdi Mutlaq under the supervision of Professor Seyyed Mohammed Khamenei in 1363 pages by the Sadra Islamic Philosophy Institute. Different lists of verses, traditions, people, etc. have also been provided in this book. Moreover, some of the chapters included in the two supplements of this commentary are entitled as follows: Jawami' al-tawhid bab al-nawadir, Jabr wa tafwiz, and Bab al-hydayah.