I say, and with God's guidance: It is not valid to perform it before this time; because it is required to be complete and cannot be fulfilled with the incomplete. It was narrated by Uqbah bin Amir Al-Juhani, may God be pleased with him, that the Messenger of God, peace be upon him, said: "There are three times during which the Messenger of God, 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 about to set 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. As for if it is performed during this time, it is permissible to perform it without dislike, but it is better to delay it; to perform it at the preferred time; because it does not miss out by being delayed, unlike the Asr prayer. Refer to: Al-Waqayah p. 137, and Tabyeen Al-Haqaiq 1: 85, and God knows best.