He was asked:

If someone recites the Quran during prayer and keeps count using prayer beads, does this invalidate his prayer?

He replied:

If the question means using prayer beads to count verses or repetitions of a single surah, such as “Say: He is Allah, the One,” there is nothing wrong with that. If something else is intended by the question, let the questioner clarify it. And Allah knows best.

He was asked:

When someone enters the mosque while people are praying, may he greet them aloud, or should he refrain for fear that someone unaware of the ruling might return his greeting verbally?

He replied:

Praise be to Allah. If the person praying knows how to respond with a gesture, there is nothing wrong with greeting him, just as the Companions used to greet the Prophet, may Allah bless him and grant him peace, and he would respond to them with a gesture. But if he does not know how to respond and might speak instead, one should not put him in a situation where he either invalidates his prayer or fails to give the response required of him. And Allah knows best.