This study dealt with the additions of Al-Hafiz Al-Mizzi

in his book (Tuhfat Al-Ashraf Ma’rifat Al-Afaraq), the Musnad of Usama bin Zaid, as an example that he added to the books of the three imams (Abu Masoud Al-Dimashqi, Khalaf Al-Wasiti, and Abu Al-Qasim Ibn Asakir), where the additions that Al-Hafiz Al-Mizzi added and commented on were collected, which is symbolized normally by (g). They are studied critically in modern way. The benefit of it is explained as well as the validity of the inference that results from it. We have relied on the inductive and analytical approach to reach the goals and objectives of the study. The study is made up of an introduction, in which explained the importance of research approach, procedures, objectives , limits and plan as well as three sections. The first one includes a brief introduction of Al-Mazzi and his scientific life. The second section contained an overview of his book (Tuhfat Alashraf). The third section shed light on the applied and practical part in which I studied his additions on Musnad Osama Bin Ziad, Allah blessed them both. I started writing the the exact text of the Hadith with its addition as well as its way as it was narrated by Al muzzi, refining it and studying its narrators’ chain to get to its level. Then I explain the benefit and purpose of the addition. I have found several benefit from his additions that he added to the Musnad of Almezzi, May Allah bless them both: clarifying that the hadith has more than one method and narration approving strengthening and supporting by pointing out that the narrator is the same even if the names are different as Muslim bin Abisahel who also has the name Mohammed Bin Abisahel. Clarifying the most reliable narration supported by well-kept method. I ended the research with a conclusion in which I mentioned a number of results that I came up with