It is narrated from Abu Huraira (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade performing prayer after Asr until the sun sets, and after Fajr until the sun rises.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 154
Hadith Takhrijأخرجه مسلم، صلاة المسافرين، باب الاوقات التي نهى عن الصلاة فيها (825)۔