Sahih Bukhari Volume 8, Book 73, Hadith Number 186.

Narated By Abu Sa’id Al-Khudri : A Bedouin said, “O Allah’s Apostle! Inform me about the emigration.” The Prophet said, “Waihaka (May Allah be merciful to you)! The question of emigration is a difficult one. Have you got some camels?” The Bedouin said, “Yes.” The Prophet said, “Do you pay their Zakat?” He said, “Yes.” The Prophet said, “Go on doing like this from beyond the seas, for Allah will not let your deeds go in vain.”