Sayyiduna Anas (may Allah be pleased with him) said that Sayyiduna Abu Bakr (may Allah be pleased with him) led the prayer during the final illness of the Prophet (peace and blessings be upon him), until Monday came. The people were in rows for the prayer when he (peace and blessings be upon him) lifted the curtain of the chamber and looked out. He (peace and blessings be upon him) was standing, and it seemed as if his (peace and blessings be upon him) face were a page of the Mushaf; then he (peace and blessings be upon him) smiled. We noticed him, and we were about to break off our prayers. Sayyiduna Abu Bakr (may Allah be pleased with him) sensed it and began to step back to join the row, (thinking) that the Prophet (peace and blessings be upon him) was coming out for the prayer. But he (peace and blessings be upon him) gestured: "Complete your prayer." Then the Prophet (peace and blessings be upon him) went into the chamber and let the curtain fall, and he (peace and blessings be upon him) passed away that very day.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16584