Umm Ja'far (may Allah have mercy on her) narrates from her grandmother, Sayyidah Asma' bint Umays (may Allah be pleased with her), that the Messenger of Allah (peace and blessings be upon him) prayed Zuhr at al-Sahba', then sent Ali (may Allah be pleased with him) on some errand. He returned when the Prophet (peace and blessings be upon him) had already prayed Asr. The Prophet (peace and blessings be upon him) placed his head in the lap of Ali (may Allah be pleased with him) and slept, and he did not move him (peace and blessings be upon him) until the sun set. Then the Prophet (peace and blessings be upon him) said: "O Allah! Your servant Ali held himself back for the sake of his Prophet, so bring the sun back for him." She said: So the sun rose again for him until it was high above the mountains and the earth, and Ali (may Allah be pleased with him) got up, performed ablution and prayed Asr. Then it set again, and this happened at al-Sahba'.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20753