Musnad Ahmad 27:1526

'Abd al-Samad narrated to us, Hammad narrated to us, from 'Ali ibn Zayd, from Yusuf ibn Mihran, from 'Abd Allah ibn 'Umar, that a man from the people of Kufa was with him, and he began speaking to him about al-Mukhtar. Ibn 'Umar said: "If he is as you say, then I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Indeed, before the Hour, there will be thirty lying impostors.'"