The Messenger of Allah ﷺ said, "Do not sell gold for gold, nor silver for silver, except weight for weight, like for like, equal for equal."He also said, "When the heat becomes intense, delay the prayer until it cools, for the intensity of the heat is from the blast of Hell."
حدثنا قتيبة حدثنا يعقوب يعني القارئ حدثنا سهيل عن أبيه
أن رسول الله ﷺ قال لا تبيعوا الذهب بالذهب ولا الورق بالورق إلا وزنا بوزن مثلا بمثل سواء بسواء و قال إذا اشتد الحر فأبردوا بالصلاة فإن شدة الحر من فيح جهنم
[Shakir: 11003] Its isnad is sahih. The hadith is in Muslim with its wording, 3/1209, no. 1584, and with similar wording in all the other imams.[Shakir: 11004] Its isnad is sahih, like the one before it. The hadith has already appeared many times from Abu Hurairah at 9164 and in many other places.