Expiation of sins at the conclusion of a gathering

The Messenger of Allah ﷺ said: "If anyone says these words before rising from a gathering in which there was vain talk, Allah will surely forgive him what happened in that gathering" [at-Tirmidhi 3433]:

"Glory be to You, O Allah, and praise be to You. I bear witness that there is no god but You; I seek Your forgiveness and turn to You in repentance."

"A gathering with vain talk" — i.e., one where Allah was not remembered or conversation was idle.

[at-Tirmidhi 3433; Sahih Sunan at-Tirmidhi 3433]