Sayyiduna Abdullah bin al-Sa'ib (may Allah be pleased with him) said: I was present with the Prophet (peace and blessings be upon him) in the year of the Conquest. He (peace and blessings be upon him) led the Fajr prayer, and he took off his sandals and placed them on his left side.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4258