It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "When the heat becomes intense, perform the prayer at a cooler time, because the severity of the heat is from the steam of Hell." Imam Darimi (may Allah have mercy on him) said: In my view, this applies to the time when the heat is distressing.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1241
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده ضعيف من أجل عبد الله بن صالح ولكن الحديث متفق عليه، [مكتبه الشامله نمبر: 1243]
Hadith Takhrijعبدالله بن صالح کی وجہ سے اس روایت کی سند ضعیف ہے، لیکن یہ حدیث صحیح متفق علیہ ہے۔ دیکھئے: [بخاري 536] ، [مسلم 615، و أصحاب السنن الأربعة] و [أبويعلی 5871] ، [ابن حبان 1504]
Brief Explanation
(Commentary on Hadith 1240)
In this hadith, there is an instruction to perform the Zuhr (noon) prayer with some delay during intense heat, but not to such an extent that the time for the Asr (afternoon) prayer arrives. Some people perform the Zuhr prayer when the shadow becomes equal to the object (one shadow-length), but it is established from the blessed ahadith that the beginning time for Asr is when the shadow becomes equal to the object (one shadow-length), and this is also the opinion of the majority of scholars.