The Times of Prayer
Malik :: Book 1 : Hadith 1.7.29
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."