Hadith
أَخْبَرَنِي إِبْرَاهِيمُ بْنُ الْحَسَنِ الْمِقْسَمِيُّ، عَنْ حَجَّاجٍ، عَنِ ابْنِ جُرَيْجٍ، عَنْ عَطَاءٍ، أَخْبَرَنِي ابْنُ أَبِي مُلَيْكَةَ، عَنْ عَائِشَةَ، قَالَتْ فَقَدْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم ذَاتَ لَيْلَةٍ فَظَنَنْتُ أَنَّهُ ذَهَبَ إِلَى بَعْضِ نِسَائِهِ فَتَجَسَّسْتُهُ فَإِذَا هُوَ رَاكِعٌ أَوْ سَاجِدٌ يَقُولُ " سُبْحَانَكَ وَبِحَمْدِكَ لاَ إِلَهَ إِلاَّ أَنْتَ " . فَقُلْتُ بِأَبِي وَأُمِّي إِنَّكَ لَفِي شَأْنٍ وَإِنِّي لَفِي شَأْنٍ آخَرَ .
It was narrated that 'Aishah said:"I noticed that the Messenger of Allah was not there one night, and I thought that he had gone to one of his other wives, so I reached out for him, and found him bowing or prostrating, and saying: 'Subhanaka wa bi hamdika la ilaha illa anta (Glory and praise be to You, there is none worthy of worship but You).' I said: 'May my father and mother be sacrificed for you; you were doing one thing, and I was thinking of something else
Sahih · Abu Ghuddah
Sunan an-Nasa'i 3961 ·Book 36, Hadith 23·Also available on sunnah.com·