Q. | If someone says salam to us while we are engaged in a canonic prayer, how do we respond?
A. | If someone says salam to you while you are engaged in a canonic prayer, it is obligatory that you immediately respond to him, but with the salam preceding the alaykum. Therefore, you may say salamun alaykum or assalamu alaykum, not alaykum assalam. Saying the latter invalidates the prayer.