Sahih Muslim
The Book on Government (Kitab Al-Imara)
Book Number: 020 / Hadith Number: 4600
It has been narrated on the authority of Abu Sa'id al-Khudari that a Bedouin asked the Messenger of Allah (may peace be upon him) about Migration. He replied: Do you talk of Hijra? The affair of Hijra is very difficult. But have you got camels? The bedouin said: Yes. He asked: Do you pay the poor-rate payable on their account? He replied: Yes. He (the Holy Prophet) said: Go on doing good deeds (across the seas), for surely God will not leave any of your deeds unrewarded.