Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
bayhaqi:5630 – Abū ʿAbdullāh al-Ḥāfiẓ And ʾAbū Saʿīd b. Abū ʿAmr > Abū al-ʿAbbās Muḥammad b. Yaʿqūb > Asīd b. ʿĀṣim > al-Ḥusayn b. Ḥafṣ > Sufyān > al-Aʿmash > al-Musayyab > Zayd b. Wahb > ʿUmar

[Machine] If the heat intensifies, let him prostrate on his garment, and if the crowd intensifies, let one of you prostrate on the back of his brother.  

البيهقي:٥٦٣٠ – أَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ وَأَبُو سَعِيدِ بْنُ أَبِي عَمْرٍو قَالَا ثنا أَبُو الْعَبَّاسِ مُحَمَّدُ بْنُ يَعْقُوبَ ثنا أَسِيدُ بْنُ عَاصِمٍ ثنا الْحُسَيْنُ بْنُ حَفْصٍ عَنْ سُفْيَانَ عَنِ الْأَعْمَشِ عَنِ الْمُسَيَّبِ عَنْ زَيْدِ بْنِ وَهْبٍ أَنَّ عُمَرَ قَالَ

إِذَا اشْتَدَّ الْحَرُّ فَلْيَسْجُدْ عَلَى ثَوْبِهِ وَإِذَا اشْتَدَّ الزِّحَامُ فَلْيَسْجُدْ أَحَدُكُمْ عَلَى ظَهْرِ أَخِيهِ