If I enter a Religious Gathering, should I give Salutations?

Question :

What is the best thing to do if a person arrives late for a lecture in College or a religious gathering and the teacher has already begun speaking, is it best to give salutations, or sit down without giving salutations?

Answer:

It is better not to give salutations if this will interrupt the class, or cause annoyance to them. However, if it does not effect them, then giving salutations is a Sunnah for every person arriving at the gathering. In view of this, he should give salutations, and if any of those sitting answers him, it is sufficient.

Question :

What reason is there for a scholar to hesitate to give a legal ruling?

Answer:

A scholar may hesitate to give a legal ruling, if he is qualified to do so, and has knowledge, because the evidences that he has seem contradictory, or it could be that he feels that the questioner is not serious, as some questioners are not searching for the truth, they only want to play around, or to know the opinion of this scholar, and a second scholar, and a third scholar, etc. In such cases, the scholar may hesitate or refuse to answer the questioner who knows, if he feels it likely that he is playing around in order to see what the people (i.e. the scholars) say, or he wants to compare some of the sayings of the people (i.e. the scholars) with others - and this is worse, for he goes around saying: "The scholar so-and-so said such and such and the scholar so-and-so said such and such." These are some of the reasons why a scholar may hesitate to deliver a ruling.

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 1 Pages 271-272