Muhammad bin Abd al-Malik bin Abi Mahdhurah narrates from his grandfather, Sayyiduna Abu Mahdhurah (may Allah be pleased with him), that he said: "O Messenger of Allah (peace and blessings be upon him), teach me the way of the adhan." In it, it says: 'Hayya 'ala al-falah, hayya 'ala al-falah' (Come to success, come to success). "If it is the morning prayer, say: 'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm' (Prayer is better than sleep, prayer is better than sleep), 'Allahu akbar, Allahu akbar, la ilaha illallah' (Allah is the Greatest, Allah is the Greatest, there is no god but Allah)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1979
Sayyiduna Abu Mahdhurah (may Allah be pleased with him) narrates similarly from the Prophet (peace and blessings be upon him), and in it is: 'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm' (Prayer is better than sleep, prayer is better than sleep) in the first adhan of the morning.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1980
It is narrated from Sayyiduna Abu Mahdhurah (may Allah be pleased with him): I was the muezzin appointed by the Prophet (peace and blessings be upon him), and in the first adhan of Fajr, after 'Hayya 'ala al-falah, hayya 'ala al-falah' (Come to success, come to success), I used to say: "'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm, Allahu akbar, Allahu akbar, la ilaha illallah' (Prayer is better than sleep, prayer is better than sleep, Allah is the Greatest, Allah is the Greatest, there is no god but Allah)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1981
It is narrated from Hafs bin Umar bin Sa'd al-Mu'adhdhin that Sayyiduna Sa'd (may Allah be pleased with him) was the muezzin appointed by the Prophet (peace and blessings be upon him). Hafs said: My family told me that Sayyiduna Bilal (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) to give the call for the morning prayer, and they said: He (peace and blessings be upon him) is asleep. Sayyiduna Bilal (may Allah be pleased with him) called out at the top of his voice: 'Al-salatu khayrun min al-nawm' (Prayer is better than sleep), and then it was made a fixed part of the morning prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1982
Sa'id bin al-Musayyib (may Allah have mercy on him), relating the story of the dream of Abdullah bin Zayd (may Allah be pleased with him), said: Then Bilal (may Allah be pleased with him) added these words to the adhan: 'Al-salatu khayrun min al-nawm' (Prayer is better than sleep). Bilal (may Allah be pleased with him) came, after giving the adhan for the Fajr prayer, to inform the Prophet (peace and blessings be upon him) of the prayer, and he was told that the Prophet (peace and blessings be upon him) was asleep. Bilal (may Allah be pleased with him) called out at the top of his voice: 'Al-salatu khayrun min al-nawm' (Prayer is better than sleep), and then it was made a fixed part of the morning adhan.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1983
It is narrated from Sayyiduna Anas (may Allah be pleased with him): It is from the sunnah that in the morning adhan, after 'Hayya 'ala al-falah' (Come to success), the muezzin says: 'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm' (Prayer is better than sleep, prayer is better than sleep), 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), 'La ilaha illallah' (There is no god but Allah).
This chain is sahih (authentic).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1984
It is narrated from Sayyiduna Nu'aym bin al-Nahham (may Allah be pleased with him): On a cold morning I was with my wife under her cloak when the caller of the Messenger of Allah (peace and blessings be upon him) called for the morning prayer. When I heard it, I said: If only he would say: 'And whoever stays seated, there is no blame (on him).' He said: When he said 'Al-salatu khayrun min al-nawm' (Prayer is better than sleep), he said: 'And whoever stays seated, there is no blame on him.'
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1985
(a) It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that in the first adhan, after 'Hayya 'ala al-falah', there was: 'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm' (Prayer is better than sleep, prayer is better than sleep).
(b) It is narrated from Ibn Umar (may Allah be pleased with them both) that 'Hayya 'ala al-falah, hayya 'ala al-falah, al-salatu khayrun min al-nawm' (Come to success, come to success, prayer is better than sleep) was said twice in the first adhan, that is, in the morning adhan.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1986
It is narrated from Sayyiduna Umar (may Allah be pleased with him) that he said to the muezzin: When you reach 'Hayya 'ala al-falah' (Come to success) in Fajr, say: 'Al-salatu khayrun min al-nawm, al-salatu khayrun min al-nawm' (Prayer is better than sleep, prayer is better than sleep).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1987