Abu Darda' (Allah be pleased with him) reported: We set out during the month of Ramadan with the Messenger of Allah (ﷺ) in such an intense heat that one of us would place his hand over his head (in order to protect himself) against the excessive heat, and none among us was observing the fast, except the Messenger of Allah (ﷺ) and 'Abdullah b. Rawaha.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا دَاوُدُ بْنُ رُشَيْدٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، عَنْ سَعِيدِ بْنِ عَبْدِ الْعَزِيزِ، عَنْ إِسْمَاعِيلَ، بْنِ عُبَيْدِ اللَّهِ عَنْ أُمِّ الدَّرْدَاءِ، عَنْ أَبِي الدَّرْدَاءِ، - رضى الله عنه - قَالَ خَرَجْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي شَهْرِ رَمَضَانَ فِي حَرٍّ شَدِيدٍ حَتَّى إِنْ كَانَ أَحَدُنَا لَيَضَعُ يَدَهُ عَلَى رَأْسِهِ مِنْ شِدَّةِ الْحَرِّ وَمَا فِينَا صَائِمٌ إِلاَّ رَسُولُ اللَّهِ صلى الله عليه وسلم وَعَبْدُ اللَّهِ بْنُ رَوَاحَةَ .
sunnah.com