Sahih al-Bukhari, Hadith 5755 ⓘ
Narrated Abu Huraira: The Prophet said, "There is no Tiyara and the best omen is the Fal," Somebody said, "What is the Fal, O Allah's Messenger?" He said, "A good word that one of you hears (and takes as a good omen).
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، أَخْبَرَنَا هِشَامٌ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " لاَ طِيَرَةَ، وَخَيْرُهَا الْفَأْلُ ". قَالَ وَمَا الْفَأْلُ يَا رَسُولَ اللَّهِ قَالَ " الْكَلِمَةُ الصَّالِحَةُ يَسْمَعُهَا أَحَدُكُمْ ".
also referenced under: Book 76, Hadith 70 (In-Book) & Volume 7, Book 71, Hadith 651 (USC-MSA)