Etiquettes

Saying "Khuda Haafiz"

Q: What is the ruling regarding saying "Khuda Haafiz" when departing from a meeting? I know that it is best to say "Assalamu Alaykum", but since "Khuda Haafiz" also has a good meaning, would it at least be better than saying "Goodbye"?

Replying to the Salaam

Q: Is it obligatory on us to reply if anyone says to us Assalamu Alaikum Wa Rahmatullahi Wa Baraakatuhu? What will be the extent of that reply, do we have to say Wa Alaikum Assalam Wa Rahmatullahi Wa Baraakatuhu or we can just say Wa Alaikum Assalam? Whenever I receives your reply through email, there is always written Salaam in the beginning, do I have to reply to that Salaam as well?