Nasr b. Muzahim's monograph is reported in a very limited fashion by Abu al‑Faraj in Maqatil al‑Talibiyyin1.
He seems to have had two main sources: Abu Mikhnaf, whom he reports on the authority of his mentor `Umar b. Sa'd, and Jabir b. Yazid al‑Ju'fi, whom he reports through `Amr b. Shamir. Nasr b. Muzahim uses both of these sources in his monograph on the Battle of Siffin. If his full work had survived, we would have had a much fuller Shi’i version of the account, as Nasr was himself a Shi’i, and tended to favour the Shi’i tradition.
- 1. Abu al‑Faraj, op. cit., pp. 51‑81.