Prayer: If Someone Says “Al-salāmu ʿAlaykum Jamīʿan” to a Group, Must a Person Praying Also Reply Even If Others Already Did?

Practical Laws of Islam as per the teachings of Imam Khamenei

Prayer: If Someone Says “Al-salāmu ʿAlaykum Jamīʿan” to a Group, Must a Person Praying Also Reply Even If Others Already Did?

English:

Question #511:

A person enters upon a group of people and salutes them with the words "al-salāmu alaykum jamī‘an (peace be upon all of you)". If one of the people in the group is praying, is it obligatory for him to answer the salutation even though someone else in the group has already replied to the greeting?

Answer #511:

If someone has already done so, the praying person should not respond.

-Imam Khamenei, Practical Laws of Islam, Importance and Conditions of Prayer