Is it mustahabb
    for one who gets up to leave a gathering to say salaam to those who are still sitting?
Question

                Is it mustahabb for one who gets up to
      leave a gathering to say salaam to those who are still sitting, or not? Is there any
      hadeeth about this or not?
Praise be to Allah.It is Sunnah to do that. Abu Hurayrah (may Allaah be
    pleased with him) reported that the Prophet 
 (peace and blessings of Allaah be upon him)
    said: “When one of you joins a gathering, let him say salaam. When he wants to get up
    and leave, let him say salaam. The former is not more important than the latter.”
(Reported by al-Tirmidhi, who said, It is a hasan hadeeth. ).