Sahih al-Bukhari 33:15
Narrated Abu Sa`id:
We practiced I`tikaf with Allah's Messenger (ﷺ) in the middle ten days (of Ramadan). In the morning of the twentieth (of Ramadan) we shifted our baggage, but Allah's Messenger (ﷺ) came to us and said, "Whoever was m I`tikaf should return to his place of I`tikaf, for I saw (i.e. was informed about the date of) this Night (of Qadr) and saw myself prostrating in mud and water." When I returned to my place the sky was overcast with clouds and it rained. By Him Who sent Muhammad with the Truth, the sky was covered with clouds from the end of that day, and the mosque which was roofed with leafstalks of date palm trees (leaked with rain) and I saw the trace of mud and water over the nose of the Prophet (ﷺ) and its tip.
Reference
Sahih al-Bukhari 33:15
In-book reference
Book 33, Hadith 15
Arabic Text
حَدَّثَنَا عَبْدُ الرَّحْمَنِ، حَدَّثَنَا سُفْيَانُ، عَنِ ابْنِ جُرَيْجٍ، عَنْ سُلَيْمَانَ الأَحْوَلِ، خَالِ ابْنِ أَبِي نَجِيحٍ عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي سَعِيدٍ،. قَالَ سُفْيَانُ وَحَدَّثَنَا مُحَمَّدُ بْنُ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي سَعِيدٍ،. قَالَ وَأَظُنُّ أَنَّ ابْنَ أَبِي لَبِيدٍ، حَدَّثَنَا عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي سَعِيدٍ ـ رضى الله عنه ـ قَالَ اعْتَكَفْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم الْعَشْرَ الأَوْسَطَ، فَلَمَّا كَانَ صَبِيحَةَ عِشْرِينَ نَقَلْنَا مَتَاعَنَا فَأَتَانَا رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ كَانَ اعْتَكَفَ فَلْيَرْجِعْ إِلَى مُعْتَكَفِهِ فَإِنِّي رَأَيْتُ هَذِهِ اللَّيْلَةَ، وَرَأَيْتُنِي أَسْجُدُ فِي مَاءٍ وَطِينٍ ". فَلَمَّا رَجَعَ إِلَى مُعْتَكَفِهِ، وَهَاجَتِ السَّمَاءُ، فَمُطِرْنَا فَوَالَّذِي بَعَثَهُ بِالْحَقِّ لَقَدْ هَاجَتِ السَّمَاءُ مِنْ آخِرِ ذَلِكَ الْيَوْمِ، وَكَانَ الْمَسْجِدُ عَرِيشًا، فَلَقَدْ رَأَيْتُ عَلَى أَنْفِهِ وَأَرْنَبَتِهِ أَثَرَ الْمَاءِ وَالطِّينِ.