Musnad Ahmad 31:628

Muhammad ibn Mus'ab narrated to us, he said: Al-Awza'i narrated to us, from Al-Zuhri, from 'Ata' ibn Yazid al-Laythi, from Abu Sa'id al-Khudri, that a Bedouin came to the Prophet, peace and blessings of Allah be upon him, and said: "O Messenger of Allah, I have camels and I wish to migrate (Hijrah), so what do you command me?" He said: "Do you give some of them as a gift?" He said: "Yes." He said: "And do you pay their Zakat?" He said: "Yes." He said: "And do you milk them on the day they are watered?" He said: "Yes." He then said: "Go, and work beyond the seas, for Allah will not leave anything of your deeds, and the matter of migration is severe."