Sayyiduna Jabir (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) fell ill, and we prayed behind him (peace and blessings be upon him). He (peace and blessings be upon him) was sitting, and Sayyiduna Abu Bakr (may Allah be pleased with him) was making the people hear his (peace and blessings be upon him) takbir. He (peace and blessings be upon him) looked towards us while we were praying standing, so he (peace and blessings be upon him) gestured to us, and then we prayed sitting along with him (peace and blessings be upon him). When he (peace and blessings be upon him) had said the salam, he said: "You were about to do as the people of Persia and Rome do: they stand before their kings while the kings are seated. Do not do so. Follow your imams: if he leads the prayer standing, then pray standing, and if he leads the prayer sitting, then pray sitting."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5935
Sayyidah Aishah (may Allah be pleased with her) said: When the Prophet (peace and blessings be upon him) fell ill with the illness in which he (peace and blessings be upon him) passed away, he (peace and blessings be upon him) ordered that Abu Bakr should lead the prayer. Abu Bakr (may Allah be pleased with him) was in the prayer when he (peace and blessings be upon him) came. When Abu Bakr (may Allah be pleased with him) saw him, he began to step back. He (peace and blessings be upon him) gestured: "Lead the prayer." Abu Bakr (may Allah be pleased with him) remained standing, and the Prophet (peace and blessings be upon him) sat beside him; he (peace and blessings be upon him) was leading the prayer, and Abu Bakr (may Allah be pleased with him) was making the people hear his (peace and blessings be upon him) takbir.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5936