Musnad Ahmad 30:1311

Uthman ibn Umar narrated to us, Ibn Abi Dhi'b informed us, from al-Zuhri, from Nafi', the freed slave of Abu Qatadah, from Abu Hurayrah, that the Prophet (peace and blessings of Allah be upon him) said: "How will you be when 'Isa ibn Maryam descends among you, and your Imam is from among you?"