8.18 (It is permissible) to offer Salat (prayer) on roofs, a pulpit or wood
٨۔١٨ باب الصَّلاَةِ فِي السُّطُوحِ وَالْمِنْبَرِ وَالْخَشَبِ
[Machine] Abu Abdullah said, "Al-Hasan did not see any problem in praying on corpses or bridges, even if urine was flowing under it, above it, or in front of it, as long as there is a barrier between them." Abu Huraira prayed on the back of the mosque behind the Imam, and Ibn Umar prayed on the snow.
قَالَ أَبُو عَبْدِ اللَّهِ وَلَمْ يَرَ الْحَسَنُ بَأْسًا أَنْ يُصَلَّى عَلَى الْجَمْدِ وَالْقَنَاطِرِ، وَإِنْ جَرَى تَحْتَهَا بَوْلٌ أَوْ فَوْقَهَا أَوْ أَمَامَهَا، إِذَا كَانَ بَيْنَهُمَا سُتْرَةٌ. وَصَلَّى أَبُو هُرَيْرَةَ عَلَى ظَهْرِ الْمَسْجِدِ بِصَلاَةِ الإِمَامِ. وَصَلَّى ابْنُ عُمَرَ عَلَى الثَّلْجِ.