The Book of Mosques and Places of Prayer
5/33. Chapter:
It is recommended to pray Zuhr at the beginning of its time when there is no intense heat
Sahih Muslim
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، عَنْ غَالِبٍ الْقَطَّانِ، عَنْ بَكْرِ بْنِ عَبْدِ اللَّهِ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كُنَّا نُصَلِّي مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي شِدَّةِ الْحَرِّ فَإِذَا لَمْ يَسْتَطِعْ أَحَدُنَا أَنْ يُمَكِّنَ جَبْهَتَهُ مِنَ الأَرْضِ بَسَطَ ثَوْبَهُ فَسَجَدَ عَلَيْهِ .
Anas b. Malik reported: We used to say (the noonprayer) with the Messenger of Allah (ﷺ) in the intense heat, but when someone amongst us found it hard to place his forehead on the ground, he spread his cloth and prostrated on it.
Reference : Sahih Muslim 620In-book reference : Book 5, Hadith 241USC-MSA web (English) reference : Book 4, Hadith 1296