I used to devote myself (observe i'tikaf) during these ten (nights). Then I started devoting myself in the last ten (nights). And he who desires to observe i'tikaf along with me should spend the night) at his place of i'tikaf. And I saw this night (Lailat-ul-Qadr) but I forgot it (the exact night) ; so seek it;In the last ten nights on odd numbers. I saw (the glimpses of that dream) that I was prostrating in water and mud. Abu Sa'id al-Khudri said: It rained on the twenty-first night and the water dripped (from the roof) of the mosque at the place where the Messenger of Allah ﷺ observed prayer. I looked at him and as he completed the dawn prayer, (I found) his face was wet with mud and water. (Using translation from Muslim 1167a)   

كَانَ رَسُولُ اللهِ ﷺ يُجَاوِرُ فِي الْعَشْرِ الَّتِي وَسَطَ الشَّهْرِ فَإِذَا كَانَ مِنْ حِينِ يَمْضِي عِشْرِينَ لَيْلَةً وَيَسْتَقْبِلُ إِحْدَى وَعِشْرِينَ رَجَعَ إِلَى مَسْكَنِهِ وَرَجَعَ مَنْ كَانَ يُجَاوِرُ مَعَهُ ثُمَّ إِنَّهُ أَقَامَ فِي شَهْرٍ جَاوَرَ فِيهِ تِلْكَ اللَّيْلَةَ الَّتِي كَانَ يَرْجِعُ فِيهَا فَخَطَبَ النَّاسَ فِيهَا فَأَمَرَهُمْ بِمَا شَاءَ اللهُ ثُمَّ قَالَ إِنِّي كُنْتُ أُجَاوِرُ هَذِهِ الْعَشْرَ ثُمَّ بَدَا لِي أَنْ أُجَاوِرَ هَذِهِ الْعَشْرَ الْأَوَاخِرَ فَمَنِ اعْتَكَفَ مَعِي فَلْيَبِتْ فِي مُعْتَكَفِهِ وَقَالَ رَأَيْتُ هَذِهِ اللَّيْلَةَ ثُمَّ أُنْسِيتُهَا فَالْتَمِسُوهَا فِي الْعَشْرِ الْأَوَاخِرِ فِي وِتْرٍ وَقَدْ رَأَيْتُنِي أَسْجُدُ فِي مَاءٍ وَطِينٍ قَالَ أَبُو سَعِيدٍ الْخُدْرِيُّ مُطِرْنَا لَيْلَةَ إِحْدَى وَعِشْرِينَ فَوُكِفَ الْمَسْجِدُ فِي مُصَلَّى رَسُولِ اللهِ ﷺ فَنَظَرْتُ إِلَيْهِ وَقَدِ انْصَرَفَ مِنْ صَلَاةِ الصُّبْحِ وَوَجْهُهُ مُبْتَلٌّ طِينًا وَمَاءً  

[Machine] We memorized the Night of Decree in a group from the Quraysh. So I stood and went to Abu Sa'id al-Khudri and said, "O Abu Sa'id, won't you come out with us to the date-palm trees?" He replied, "Yes." So he called for a garment and wore it, then we went out and I asked him, "Did you hear the Messenger of Allah ﷺ mentioning anything about the Night of Decree?" He replied, "Yes. We performed Itikaf with the Messenger of Allah ﷺ during the middle ten days of Ramadan. When the twenty-first (night of Ramadan) came, he commanded us to keep on Itikaf and said, 'Whoever has performed Itikaf with me should continue it. I have been shown that tonight is the Night of Decree. So search for it in the odd nights of the last ten nights of Ramadan. I saw myself prostrating in mud and water on that night. At the time the roof of the mosque was made of leaves of date-palm trees. At that time, while I was watching him, I saw mud and water on the forehead and the nose of the Prophet ﷺ till I saw the trace of mud and water on the forehead of the Prophet ﷺ and on the tip of his nose."  

تَذَاكَرْنَا لَيْلَةَ الْقَدْرِ فِي نَفَرٍ مِنْ قُرَيْشٍ فَقُمْتُ حَتَّى أَتَيْتُ أَبَا سَعِيدٍ الْخُدْرِيَّ فَقُلْتُ يَا أَبَا سَعِيدٍ أَلَا تَخْرُجُ بِنَا إِلَى النَّخْلِ؟ قَالَ نَعَمْ فَدَعَا بِخَمِيصَةٍ فَأَدْخَلَهَا عَلَيْهِ فَخَرَجْنَا فَقُلْتُ هَلْ سَمِعْتَ رَسُولَ اللهِ ﷺ يَذْكُرُ لَيْلَةَ الْقَدْرِ؟ قَالَ نَعَمْ اعْتَكَفْنَا مَعَ رَسُولِ اللهِ ﷺ الْعَشْرَ الْأَوْسَطَ مِنْ رَمَضَانَ فَلَمَّا كَانَ صَبِيحَةُ عِشْرِينَ مِنْ رَمَضَانَ قَامَ فِينَا فَقَالَ مَنْ كَانَ خَرَجَ فَلْيَرْجِعْ فَإِنِّي أُرِيتُ لَيْلَةَ الْقَدْرِ فَنَسِيتُهَا فَالْتَمِسُوهَا فِي الْعَشْرِ الْأَوَاخِرِ فِي وِتْرٍ وَإِنِّي أُرِيتُ أَنِّي أَسْجُدُ فِي مَاءٍ وَطِينٍ وَمَا نَرَى فِي السَّمَاءِ قَزَعَةً فَأُقِيمَتِ الصَّلَاةُ وَثَارَتْ سَحَابَةٌ فَمُطِرْنَا حَتَّى سَالَ سَقْفُ الْمَسْجِدِ وَسَقْفُهُمْ يَوْمَئِذٍ مِنْ جَرِيدِ النَّخْلِ فَرَأَيْتُ رَسُولَ اللهِ ﷺ يَسْجُدُ فِي الطِّينِ وَالْمَاءِ حَتَّى رَأَيْتُ أَثَرَ الطِّينِ عَلَى أَرْنَبَتِهِ وَجَبْهَتِهِ