Masruq (may Allah have mercy on him) says: I asked Sayyidah Aishah (may Allah be pleased with her) about the deeds of the Prophet (peace and blessings be upon him), and she said: The Prophet (peace and blessings be upon him) loved most the deeds that are done constantly. I said: When would he (peace and blessings be upon him) get up to stand in prayer? She said: When he (peace and blessings be upon him) heard the crowing of the rooster.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4659