Sahih al-Bukhari 1208
Sahih al-Bukhari · Book 21: Actions while Praying · Spreading the clothes over the site of prostration
Narrated Anas bin Malik:
حَدَّثَنَا مُسَدَّدٌ ، حَدَّثَنَا بِشْرٌ ، حَدَّثَنَا غَالِبٌ ، عَنْ بَكْرِ بْنِ عَبْدِ اللَّهِ ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ قَالَ كُنَّا نُصَلِّي مَعَ النَّبِيِّ صلى الله عليه وسلم فِي شِدَّةِ الْحَرِّ، فَإِذَا لَمْ يَسْتَطِعْ أَحَدُنَا أَنْ يُمَكِّنَ وَجْهَهُ مِنَ الأَرْضِ بَسَطَ ثَوْبَهُ فَسَجَدَ عَلَيْهِ.
We used to pray with the Prophet (ﷺ) in scorching heat, and if someone of us could not put his face on the earth (because of the heat) then he would spread his clothes and prostrate over them.