When hearing a rooster crow, one should beg Allah Ta‘ala for His grace.
عن أبي هريرة، أن النبي صلى الله عليه وسلم، قال: إذا سمعتم صياح الديكة، فسلوا الله تعالى من فضله، فإنها رأت ملكا، وإذا سمعتم نهيق الحمار، فتعوذوا بالله من الشيطان، فإنها رأت شيطانا (صحيح البخاري، الرقم: 5102)
Hazrat Abu Hurairah (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “When you hear a rooster crow, then you should ask Allah Ta‘ala to grant you His grace, for it (the rooster many a time crows because it) has seen an angel. And when you hear a donkey bray, then you should seek the protection of Allah Ta‘ala from shaytaan, for it (the donkey many a time brays as it) has seen a shaytaan.”