(a) It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that the muezzin of the Messenger of Allah (peace and blessings be upon him) gave the call to prayer for Zuhr, and he (peace and blessings be upon him) said to him the words "Abrid, abrid" and "Intazir, intazir," that is, "Wait." Then he said: "The intensity of the heat is from the breath of Hell. When the weather is very hot, delay the prayer and then pray it." Sayyiduna Abu Dharr (may Allah be pleased with him) said: (It was delayed) so long that we saw the shadows of the small mounds.
(b) In this there is something like an indication that the order to wait for the cool came after the call to prayer, and that the call to prayer was given at the beginning of the time.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2062