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 الَّذِي فِي وَسَطِ الشَّهْرِ فَإِذَا كَانَ مِنْ حِينِ تَمْضِي عِشْرُونَ لَيْلَةً وَيَسْتَقْبِلُ إِحْدَى وَعِشْرِينَ يَرْجِعُ إِلَى مَسْكَنِهِ وَيَرْجِعُ مَنْ كَانَ مَعَهُ ثُمَّ إِنَّهُ أَقَامَ فِي شَهْرٍ جَاوَرَ فِيهِ تِلْكَ اللَّيْلَةَ الَّتِي كَانَ يَرْجِعُ فِيهَا فَخَطَبَ النَّاسَ فَأَمَرَهُمْ بِمَا شَاءَ اللهُ ثُمَّ قَالَ «إِنِّي كُنْتُ أُجَاوِرُ هَذِهِ الْعَشْرَ ثُمَّ بَدَا لِي أَنْ أُجَاوِرَ هَذِهِ الْعَشْرَ الْأَوَاخِرَ فَمَنْ كَانَ اعْتَكَفَ مَعِي فَلْيَثْبُتْ فِي مُعْتَكَفِهِ وَقَدْ رَأَيْتُ هَذِهِ اللَّيْلَةَ فَأُنْسِيتُهَا فَالْتَمِسُوهَا فِي الْعَشْرِ الْأَوَاخِرِ فِي كُلِّ وِتِرَ وَقَدْ رَأَيْتُنِي أَسْجُدُ فِي مَاءٍ وَطِينٍ» قَالَ أَبُو سَعِيدٍ الْخُدْرِيِّ مُطِرْنَا لَيْلَةَ إِحْدَى وَعِشْرِينَ فَوَكَفَ الْمَسْجِدُ فِي مُصَلَّى رَسُولِ اللهِ ﷺ فَنَظَرْتُ إِلَيْهِ وَقَدِ انْصَرَفَ مِنْ صَلَاةِ الصُّبْحِ وَوَجْهُهُ مُبْتَلٌّ طِينًا وَمَاءً