What is the ruling on one who fears showing off (riya') when performing acts of obedience, such as giving charity or displaying verses and invocations, and is this considered showing off? And do pictures in the house prevent angels from entering?

Fear of riya' (showing off) is legitimate, but abandoning good deeds because of it is a satanic trick. A Muslim must strive against his own soul to correct his intention and frequently recite the supplication: "O Allah, we seek refuge in You from associating anything with You knowingly, and we seek Your forgiveness for what we do not know."

The hanging of photographic images on walls is prohibited by the majority of scholars because it can lead to glorification, unless there is an assurance that no fitnah (temptation/strife) will arise. Therefore, it is preferable not to hang them, and a Muslim should strive to convince his family to remove them with wisdom and good counsel.

As for the verse: "Upon you is [the responsibility for] yourselves. Those who have gone astray will not harm you when you have been guided," its meaning is that whoever fulfills his obligations of enjoining good and forbidding evil will not be harmed by the shortcomings of others.