Ruling 1124 — Prayer (Ṣalāh)

One must immediately reply to salām, irrespective of whether he is performing prayers or not. If a person intentionally or due to forgetfulness delays his reply to salām to the extent that were he to reply to it, it would not be considered a reply to that initial salām, then in the event that he is performing prayers, he must not reply; and if he is not performing prayers, replying is not obligatory.