Sahih Bukhari Volume 3, Book 34, Hadith Number 423.

Narated By ‘Urwa bin Az-Zubair : Hakim bin Hizam said, “O Allah’s Apostle! I used to do good deeds in the Pre-lslamic period of Ignorance, e.g., keeping good relations with my Kith and kin, manumitting slaves and giving alms. Shall I receive a reward for all that?” Allah’s Apostle replied, “You embraced Islam with all the good deeds which you did in the past.”