A new source in Persian written by Zahiruddin b. Nasireddin-i Mar'asi, has been recently detected. Zahiruddin is generally known with his works called Tarih-i Taberistan, Ruyan u Mazenderdn and Tarih-i Gilan, which are important sources of the medieval history. This new work includes events of Timur's lifetime and it is a muntehab work based on sources written about the Timurids until that time. It was discovered that one of the sources of the work is Zafername of Yezdi. In addition to his borrowings from the previous works, Zahiruddin also gives important details from narrations of the witnesses and participants of the period's events. The sources he consulted were his father Nasireddin, who had personally attended to Timur's campaigns in Anatolia and Syria, and his uncle Gwaseddin and his uncle's son Abdulvahap. According to Zahiruddin, Yezdi's narrations concerning Yildirim Bayezid's capture and conversations between Bayezid and Timur were not accurate. He narrates these events according to the accounts of his uncle Giyaseddin, who had been present in the tent of Timur when Bayezid was brought there, and of his uncle's son Abdulvahap, who had been rewarded by Timur for his services during the Ankara War.