I have studied the works of the great Hafiz Imam, Dawud al-Tayalisi al-Basri (died in 204 H); such great reliable imam who used to report thirty thousand hadiths from memory. It was known that whenever Shu’ba’s hadith session came to an end, Abu Dawud al-Tayalisi would take his seat and report all that was told during that session from memory. I have tracked all his contributions, identified their locations in the world libraries of paper books, and reviewed the studies conducted about them, as well as any related publications. I was keen on tracing all his books; published ones, manuscripts and even those missing works with the attempt to assimilate as much as I could. I have also intensively examined the studies that have been written about or ased on him, including annotations, appendices, classifications, categorizations, etc. This is a useful tracking study for scholars and for those who are interested in that branch of science, as it collects the scattered works of such great imam found in the enormous libraries, especially the written copies of his precious book “al-Musnad”, the manuscripts of which are found in all four corners of the world. A written copy is currently kept at Topkapı Sarayı of Ahmed III, another with İsmail Hakkı İzmirli, one at Asfia Library, one with Khoda Bakhsh, one with Rasheed Dahdah, and several other written copies are kept in the Library of Awqaf Baghdad, in addition to a copy kept at Karl Marx Blaisezeg. Photocopies of these copies are kept at Jumat Al Majid Center in Dubai, and at the Institute of Manuscripts in Cairo. There may be a number of volumes for that book in the same library, while other libraries may have several written copies of it. I have described these copies in detail; listing their numbers, the number of pages, writing year, and registration numbers, as well as any other details I could find for each version in a brief and focused way.Based on this study and the tracking research, I found out that this “Musnad” was not compiled by Abu Dawud Tilaisi himself; instead, it was compiled for him by some Huffaz (hadith scholars) from Khorasan, and this applies in particular on those hadiths reported by Younis Ibn Habib from Abu Dawud. According to Al-Hafiz al-Zahabi in his “Syer al-Nubala’,: Abu Mas'ud al-Razi compiled (Musnad Abu Dawud) for Yunus Ibn Habib”, and the same claim was supported by Ibn Hajjar who said in Al-Mu'ajam Al-Mofahras, no. 481: “Musnad Abu Dawud Ibn Sulayman Ibn Dawud al-Tilaisi includes a collection of hadiths reported by Yunus ibn Habib from Abu Dawud and compiled by some people from Isphahan. So we can find some narrations for Younus Ibn Habib from scholars other than Abu Dawud al-Tilaisi.