Sayyidah Asma' bint Umays (may Allah be pleased with her) said: Revelation was coming down upon the Messenger of Allah (peace and blessings be upon him) while his (peace and blessings be upon him) head was in the lap of Ali (may Allah be pleased with him), so he did not pray Asr during that time until the sun had set. The Messenger of Allah (peace and blessings be upon him) said: "O Allah! Ali was in obedience to You and to Your Messenger, so bring the sun back for him." Sayyidah Asma' (may Allah be pleased with her) said: "I saw it set, and then I saw it rise again after it had set."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20761