Does a Muslim sin by making up a prayer that was missed due to a valid excuse, and how can he compensate for the sin with good deeds?

Missed prayers must be made up, as the Prophet (peace be upon him) said: "Whoever forgets a prayer, let him pray it when he remembers it; there is no expiation for it except that." If someone misses a prayer due to an excuse, such as sleep or forgetfulness, they must make it up and are not sinful. However, if they do not make it up despite being able to, they are sinful. Good deeds are among the reasons for expiating bad deeds, as the Prophet (peace be upon him) said: "Be mindful of Allah wherever you are, and follow up a bad deed with a good one that will erase it."