Mishkat al-Masabih 23 Medicine and Spells كتاب الطب والرقى 60

عَنْ أَبِي هُرَيْرَةَ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «لَا طِيَرَةَ وَخَيْرُهَا الْفَأْلُ» قَالُوا: وَمَا الْفَأْلُ؟ قَالَ: «الْكَلِمَةُ الصَّالِحَة يسْمعهَا أحدكُم»

Abu Huraira told of hearing God’s messenger say, “There should be no taking of omens, but the best type is the good omen.” He was asked what a good omen was and replied, “A good word which one of you hears.” (Bukhari and Muslim.)