Abu Abd al-Rahman al-Sulami (may Allah have mercy on him) said: Sayyiduna Ali (may Allah be pleased with him) came out of this door and said: This is the best time for witr. Then the iqamah was called at that very time.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4524