Bilāl made a call to prayer before the break of dawn. The Prophet (may Allah's peace and blessings be upon him) therefore commanded him to return and make a call: Lo! The slave of Allah slept. Lo! The slave of Allah slept
Authentic hadithعن عبدالله بن عمر رضي الله عنهما أن بلالا أذَّنَ قبل طلوع الفجر، فأمره النبي صلى الله عليه وسلم أن يرجع فينادي: «ألا إن العبد قد نام، ألا إن العبد قد نام».
‘Abdullāh ibn ‘Umar (may Allah be pleased with him) reported that Bilāl made a call to prayer before the break of dawn. The Prophet (may Allah's peace and blessings be upon him) therefore commanded him to return and make a call: "Lo! The slave of Allah slept. Lo! The slave of Allah slept."
Explanation
This Hadīth clarifies that if the Muezzin mistimed calling the Adhān, he is to declare that he was mistaken. The Prophet (may Allah's peace and blessings be upon him) ordered Bilāl, when he mistimed calling the Adhān, to call out to the people: "Lo! The slave of Allah slept."
Source · Narrated by Abu Daoud
From the Hadith Encyclopedia (hadeethenc.com).