Sayyiduna Mughirah bin Shu’bah (may Allah be pleased with him) narrates that the Prophet Muhammad (peace and blessings be upon him) performed (so many voluntary) prayers that his blessed feet became swollen. It was said to him that indeed Allah Almighty has forgiven your past and future sins (then why do you undergo so much hardship?). He (peace and blessings be upon him) replied:“Should I not be a grateful servant (to my Lord)?”