Is it permissible for a person to perform all good deeds in secret and not display any of them before people, knowing that "abandoning a good deed out of fear of showing off is showing off itself," and is this statement correct? If it is correct, how is it considered showing off? And is it permissible for one to wait for people to leave before performing good deeds in order to attain greater sincerity, and is this considered showing off?

It is permissible to conceal deeds that the Sharia has not commanded to be publicized. Concealment is preferred when there is fear of showing off (riya'). Showing off is forbidden, and abandoning good deeds out of fear of it is a deception from Satan; in fact, it is itself a form of showing off. Therefore, it is not permissible for a Muslim to abandon obligatory duties out of fear of showing off; rather, they must perform them and strive against their self and Satan. If Satan whispers such thoughts, one should turn away from them and increase in obedience. Scholars have made an exception for abandoning good deeds when there is a fear of harm or backbiting, as this is not considered showing off but rather mercy. However, abandoning supererogatory acts out of fear of praise that might be detrimental or lead to temptation is permissible.