AAaishah رضي الله عنها reported that the Messenger of Allah (SAWS) was given a sheep and he ordered for it’s distribution. When the servant would come back (from distributing it), AAaishah would ask: ‘What did they say?’, he replied: They would supplicate:
بارَكَ اللهُ فيكُمْ.
‘May Allah bless you all.’
…AAaishah would then say:
وَفيهِـمْ بارَكَ الله.
‘and may Allah bless them.’
…we return their supplication in a similar way and our reward remains with us.
This supplication is used whenever one initially thinks a casual event or occurrence to foretell good or evil, using it as a basis to determine which action he should undertake, but he then denounces such a link, relies on Allah and then says this supplication as an expiation for this act, since it falls under the category of shirk.