Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 193
Narrated Ibn 'Abbas:
Allah's Apostle said to Ibn Saiyad "I have hidden something for you in my mind; What is it?" He said, "Ad-Dukh." The Prophet said, "Ikhsa."