Reported by Abu Hurairah and Abu Sa`id
Al-Khudri (RA): The Messenger of Allah (peace be upon him) said, "When a
group of people assemble for the remembrance of Allah, the angels
surround them (with their wings), (Allah's) mercy envelops them,
Sakinah, or tranquillity descends upon them and Allah makes a mention of
them before those who are near Him.'' [Muslim]