Whenever Allah's Messenger (ﷺ) ordered the Muslims to do something, he used to order them deeds which were easy for them to do, (according to their strength and endurance). They said, "O Allah's Messenger (ﷺ)! We are not like you. Allah has forgiven your past and future sins." So Allah's Apostle became angry and it was apparent on his face. He said, "I am the most Allah fearing, and know Allah better than all of you do."
Why is the Prophet SAW getting angry from the question people asked him? And why is he replying in a way he replied in the hadith? What does one learn from this hadith?