Narrated Hudhaifa:Allah's Messenger (ﷺ) said to us, "Honesty descended from the Heavens and settled in the roots of the hearts of men (faithful believers), and then the Qur'an was revealed and the people read the Qur'an, (and learnt it from it) and also learnt it from the Sunna." Both Qur'an and Sunna strengthened their (the faithful believers') honesty. (See Hadith No. 208)
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، قَالَ سَأَلْتُ الأَعْمَشَ فَقَالَ عَنْ زَيْدِ بْنِ وَهْبٍ، سَمِعْتُ حُذَيْفَةَ، يَقُولُ حَدَّثَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم " أَنَّ الأَمَانَةَ نَزَلَتْ مِنَ السَّمَاءِ فِي جَذْرِ قُلُوبِ الرِّجَالِ، وَنَزَلَ الْقُرْآنُ فَقَرَءُوا الْقُرْآنَ وَعَلِمُوا مِنَ السُّنَّةِ ".
Bukhari
Holding Fast to the Qur'an and Sunnah • Hadith 9