The Messenger of Allah (ﷺ) instructed to recite this dua while leaving the mosque:

اَللَّهُمَّ أَجِرْنِيْ مِنَ الشَّيْطَانِ الرَّجِيْمِ

Allaahumma ajirni minash shaitaanir rajeem

O Allah, protect me from Satan the outcast.

Reference: Sahih (Ibn Hibban). Ibn Hibban: 2047