It is narrated from Sayyiduna Mughirah bin Shu’bah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) performed prayer until his feet became swollen. The people said, "Why do you endure so much hardship, when all your past and future sins have been forgiven?" The Prophet (peace and blessings be upon him) replied, "Should I not be a grateful servant of Allah?"