Call to Prayers (Adhaan)
Bukhari :: Book 1 :: Volume 11 :: Hadith 675
Narrated 'Abdullah bin 'Abi Qatada:
My father said, "The Prophet said, 'When I stand for prayer, I intend to prolong it but on hearing the cries of a child, I cut it short, as I dislike to trouble the child's mother.' "