Sahih Bukhari Volume 004, Book 052, Hadith Number 045.

Narated By Abu Said Al-Khudri : Somebody asked, "O Allah's Apostle! Who is the best among the people?" Allah's Apostle replied "A believer who strives his utmost in Allah's Cause with his life and property." They asked, "Who is next?" He replied, "A believer who stays in one of the mountain paths worshipping Allah and leaving the people secure from his mischief."