What is the ruling on extending the salutation [Assalāmu ʿAlaykum] on Friday whilst the Imām is giving the khuṭbah, and is it permissible to return the salām by gesturing with the hand in this situation?

Shaykh Ṣāliḥ al-Fawzān:

No, none of this is allowed, either extending the salutations nor returning it with the tongue or by gesture. If it is given it should be ignored and not returned.