«إِذَا سَمِعْتُمْ صِيَاحَ الدِّيَكَةِ فَاسْأَلُوا اللَّهَ مِنْ فَضْلِهِ؛ فَإِنَّهَا رَأَتْ مَلَكاً وَإِذَا سَمِعْتُمْ نَهِيقَ الْحِمَارِ فَتَعَوَّذُوا بِاللَّهِ مِنَ الشَّيطَانِ؛ فَإِنَّهُ رَأَى شَيْطَاناً».
When you hear the cock's crow, ask Allah for His favor upon you for surely it has seen an angel. When you hear the bray of a donkey, seek refuge in Allah from Satan, for surely it has seen a devil.
SourceAl-Bukhari, cf. Al-Asqalani, Fathul-Bari 6/350, Muslim 4/2092.