After a prayers, Grand-Mufti of Pakistan Mufti Mohammed Rafi’ Usmani (Allah preserve & protect him) was walking towards a door of the Masjid to exit when someone approached him, shook hands with him and began talking to him about something. During this time a second person tried to approach him and shake his hands. Respected Mufti sternly pointed with his hands to him to stay away.
He was teaching him the basic etiquette that when two people are engaged in a conversation then a third should not interfere without permission.
Instead of a verbal lesson, this practical lesson will probably prove to be much more effective.
Ramadan 1439, malfuzaat collated by Br Kaiser Nizamani