I say, and with God's help: The Asr prayer is not invalidated if it is initiated before sunset, as long as the sun has set. In contrast, the Fajr prayer is invalidated if it is initiated before sunrise, once the sun has risen; because the part that coincides with the performance is a reason for the obligation of the prayer, and the last time for Asr is an incomplete time, as it is the time of worship of the sun, thus it must be incomplete. If it is performed, it is performed as it should be, and if the invalidation occurs at sunset, it does not invalidate it. In Fajr, all of its time is complete time; because the sun is not worshipped before its rising, thus it must be complete. If the invalidation occurs at sunrise, it is invalidated; because it was not performed as it should be. And because Asr transitions to what is generally the time for prayer, unlike Fajr; because at sunrise there is an entry into dislike, and at sunset there is an exit from it. Refer to: Tabyin al-Haqaiq 1: 85-86, and al-Tawdhih 1: 206, and the change of al-Tanqih by Ibn Kamal Pasha 1: 128, and Mir'at al-Usul 1: 134-135, and Sharh al-Manar by Ibn Malik p59-60, and Sharh al-Manar by Ibn al-Ayni p60, and al-Talwih 1: 207, and God knows best.