الْأَدَبُ الْمُفْرَدُ
Al-Adab al-Mufrad 1218
Sleep and night lodging
حَدَّثَنَا مُعَاذُ بْنُ فَضَالَةَ، قَالَ: حَدَّثَنَا هِشَامٌ الدَّسْتُوَائِيُّ، عَنْ يَحْيَى هُوَ ابْنُ أَبِي كَثِيرٍ، عَنْ أَبِي سَلَمَةَ قَالَ: حَدَّثَنِي رَبِيعَةُ بْنُ كَعْبٍ قَالَ: كُنْتُ أَبِيتُ عِنْدَ بَابِ النَّبِيِّ صلى الله عليه وسلم فَأُعْطِيهِ وَضُوءَهُ، قَالَ: فَأَسْمَعُهُ الْهَوِيَّ مِنَ اللَّيْلِ يَقُولُ: سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ، وَأَسْمَعُهُ الْهَوِيَّ مِنَ اللَّيْلِ يَقُولُ: الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ.
Rabi'a ibn Ka'b related, "I used to spend the night at the door of the Prophet, (ﷺ), and I would give him his wudu' water." He said, "After a long period of the night had passed, I heard him say, 'Allah hears whoever praises Him,' and I heard him say after a long period of the night had passed, 'Praise be to Allah, Lord of the Worlds.'"
Sunnah.com reference: Book 1, Hadith 14Sahih (Al-Albani)صـحـيـح (الألباني)