اللَّهُمَّ أَعِنِّي عَلَى ذِكْرِكَ وَشُكْرِكَ وَحُسْنِ عِبَادَتِكَ
Transliteration
Allahumma a'inni 'ala dhikrika wa shukrika wa husni 'ibadatik
English meaning
O Allah, help me to remember You, to be grateful to You, and to worship You in the best manner.
When is it recited?
Recommended to recite at the end of every prayer.
Its virtue
The Prophet (PBUH) recommended Muadh ibn Jabal to recite this after every prayer.
Source
Abu Dawud, Witr 26, 1522; Nasa'i, Sahw 60, 1303