Hazrat Abdullah bin Abi Musa narrates that Sayyidah Aisha (may Allah be pleased with her) said to me that do not abandon the night prayer (Qiyam al-Lail), because the Messenger of Allah (peace be upon him) never left it. When he (peace be upon him) would become ill or feel lethargic, he would perform the Tahajjud prayer sitting. Ali bin Muslim has narrated these words: when he (peace be upon him) would become tired or feel lethargic, (he would perform Tahajjud sitting). Abu Bakr (may Allah have mercy on him) says that in my view, this Sheikh Abdullah refers to the one whom the Egyptian and Syrian narrator Abdullah bin Abi Qais mention. From him, Muawiyah bin Salih has narrated multiple traditions.