((إِذَا سَمِعْتُمْ صِيَاحَ الدِّيَكَةِ فَاسْأَلُوا اللَّهَ مِنْ فَضْلِهِ؛ فَإِنَّهَا رَأَتْ مَلَكاً وَإِذَا سَمِعْتُمْ نَهِيقَ الْحِمَارِ فَتَعَوَّذُوا بِاللَّهِ مِنَ الشَّيطَانِ؛ فَإِنَّهُ رَأَى شَيْطَاناً)).
(If you hear the crow of a rooster, ask Allah for his bounty for it has seen an angel and if you hear the braying of an ass, seek refuge in Allah for it has seen a devil.)
Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 6/350, Muslim 4/2092.