Musnad Ahmad 5:251

Yunus narrated to us, Hammad—meaning Ibn Salamah—narrated to us, from ‘Asim, from Zirr, that it was said to ‘Ali: "The killer of Az-Zubayr is at the door." ‘Ali said: "Let the killer of Ibn Safiyyah enter the Fire. I heard the Messenger of Allah (ﷺ) say: 'Every prophet has a disciple (hawari), and my disciple is Az-Zubayr ibn al-‘Awwam.'"