456 - Greeting one another is Mustahab but replying to the greeting is obligatory.
457 - Greeting a person who is preformingprayer is Makrooh.
458 - If someone greets (gives Salam) to someone who is praying the reply must be the same as the greeting. For example, if the person said Salam alaikum the reply Should be Salam alaikum, but if one is greeted with Alaikum Salam the reply is still Salam alaikum.
459 - It is not correct for someone who ispraying to give salam to others.
460 - Salam must be answered immediately.
461 - If two people greet each other at thesame time it is obligatory for both of them toanswer one another.
The Rules of Greeting
462 - It is Mustahab for one who is riding to greet ont who is walking, one is standing to greet one who is sitting, small groups to large groups and minors to elders.
463 - It is Mustahab in times other than during prayer to return a better reply than the initial greeting so if someone says, Salamun alaikum it is Mustahab to say Salamun alaikum warahmatollah.
464 - It is Makhrooh for a man (non -Mahram) to greet a woman, especially to a young woman.