Dua upon leaving the mosque
بِسمِ الله وَالصّلاةُ وَالسّلامُ عَلى رَسولِ...
بِسمِ الله وَالصّلاةُ وَالسّلامُ عَلى رَسولِ الله، اللّهُـمَّ إِنّـي أَسْأَلُكَ مِـنْ فَضْـلِك، اللّهُـمَّ اعصِمْنـي مِنَ الشَّيْـطانِ الرَّجـيم
Bismil-lah wassalatu wassalamu AAala rasoolil-lah, allahumma innee as-aluka min fadlik, allahumma iAAsimnee minash-shaytanir-rajeem
Translation
In the name of Allah, and prayers and peace be upon the Messenger of Allah. O Allah, I ask You from Your favour. O Allah, guard me from the accursed devil.
When to recite
Recited upon leaving the mosque.
Source / Reference
Ibn Majah 1/255, Abu Dawud