(It is permissible) to offer Salat (prayer) on roofs, a pulpit or wood

Sahih al-Bukhari · Book 8 · Hadith 377

حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، قَالَ حَدَّثَنَا سُفْيَانُ، قَالَ حَدَّثَنَا أَبُو حَازِمٍ، قَالَ سَأَلُوا سَهْلَ بْنَ سَعْدٍ مِنْ أَىِّ شَىْءٍ الْمِنْبَرُ فَقَالَ مَا بَقِيَ بِالنَّاسِ أَعْلَمُ مِنِّي هُوَ مِنْ أَثْلِ الْغَابَةِ، عَمِلَهُ فُلاَنٌ مَوْلَى فُلاَنَةَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم، وَقَامَ عَلَيْهِ رَسُولُ اللَّهِ صلى الله عليه و…

Narrated Abu Hazim: Sahl bin Sa`d was asked about the (Prophet's) pulpit as to what thing it was made of? Sahl replied: "None remains alive amongst the people, who knows about it better than I. It was made of tamarisk (…