Musnad Ahmad 32:1660

'Affan narrated to us, Hammad ibn Salamah narrated to us, 'Ali ibn Zayd narrated to us, he said: I think it is from Anas ibn Malik: "That the Prophet, peace and blessings of Allah be upon him, said: 'The voice of Abu Talhah is more severe against the polytheists than a battalion.'"