I say, and with God's success: It is not valid to perform it before this time; because it has become obligatory in full, and cannot be fulfilled with a partial performance. It was narrated by 'Uqbah ibn 'Amir al-Juhani, may Allah be pleased with him, that the Messenger of Allah, peace be upon him, said: "There are three times when the Messenger of Allah, peace be upon him, forbade us to pray or to bury our dead: when the sun rises until it is fully elevated, when the sun is at its zenith until it tilts, and when the sun is setting until it sets." This is found in Sahih Muslim 1: 568, Musnad al-Mustakhraj 2: 424, Sahih Ibn Hibban 3: 348, Sunan al-Tirmidhi 3: 348, and Sunan Abu Dawood 3: 208. And from Ibn Abbas, may Allah be pleased with both of them, he said: "Witnesses who are acceptable to me testified, and the one I accept most is 'Umar, that the Prophet, peace be upon him, forbade praying after dawn until the sun rises and after 'Asr until the sun sets." This is found in Sahih al-Bukhari 1: 211. As for if it is performed during this time, it is permissible to perform it without dislike, but it is preferable to delay it; so that it can be performed at the preferred time; because it does not become missed by delaying, unlike the 'Asr prayer. Refer to: Al-Wiqayah p. 137, and Tabyeen al-Haqaiq 1: 85, and Allah knows best.