Muwatta Malik 29
Sahih Graded by Salim al-Hilali Book of The Times of Prayer · Hadith 29 of 1,858وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا اشْتَدَّ الْحَرُّ فَأَبْرِدُوا عَنِ الصَّلاَةِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ " .
Yahya related to me from Malik from Abu'z Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "When the heat is fierce, wait until it gets cooler before you do the prayer, for scorching heat is from the blast of Jahannam
References
Muwatta Malik 29
In-book: Book 1, Hadith 29 Source: hadith-api (fawazahmed0)