Is a Muslim’s good deeds tainted by showing off, and what is the ruling on refraining from some good things for fear of showing off?

Satan beautifies a person's deeds for him so that he may show off to people, and he whispers to him that his deed is ostentation so that he may abandon it. The solution is to purify one's intention for Allah and to pay no attention to Satan's whispers. One should not abandon a permissible act for fear of showing off, as Imam An-Nawawi said: "It is not appropriate to abandon dhikr (remembrance of Allah) with the tongue along with the heart for fear that one might be thought to be showing off. Rather, one should remember with both and intend thereby the Face of Allah, the Mighty and Majestic." And the saying of Fudayl ibn Iyad: "Indeed, abandoning a deed for the sake of people is ostentation (riya'), and doing a deed for the sake of people is shirk (associating partners with Allah)." If the motive for obedience is religion, then it should not be abandoned for fear of ostentation; because this is one of Satan's ploys. If Satan whispers during prayer that you are showing off, then prolong it. To avoid the whispers of ostentation when doing good, seek refuge with Allah from Satan and proceed with the good deed. If you turn away from the whispers, they will vanish by Allah's permission.