Sahih Bukhari Volume 009, Book 092, Hadith Number 381.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 92. Holding Fast to the Qur'an and Sunnah
Narrated By Hudhaifa : Allah's Apostle said to us, "Honesty descended from the Heavens and settled in the roots of the hearts of men (faithful believers), and then the Quran was revealed and the people read the Quran, (and learnt it from it) and also learnt it from the Sunna." Both Quran and Sunna strengthened their (the faithful believers') honesty. (See Hadith No. 208)