Musnad Ahmad 28:546

Ya'qub ibn Ibrahim ibn Sa'd narrated to us, my father narrated to us, from Ibn Ishaq, 'Amr ibn Shu'ayb ibn Muhammad ibn 'Abd Allah ibn 'Amr ibn al-'As narrated to me, from his father, from his grandfather, he said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "There shall be no *jalab* (bringing livestock to a place other than their pasture for the sake of Zakat) and no *janab* (the collector staying away from the dwellings of the people to force them to bring their livestock to him), and their Zakat shall not be taken except in their own dwellings."