اللَّهُمَّ أَعِنِّي عَلَى ذِكْرِكَ وَشُكْرِكَ وَحُسْنِ عِبَادَتِكَ
Allahumma a'inni 'ala dhikrika wa shukrika wa husni 'ibadatik
O Allah, hilf mir, Deiner zu gedenken, Dir zu danken und Dich auf die beste Weise anzubeten.
Recite after every obligatory prayer
The Prophet (PBUH) took Muadh ibn Jabal's hand and said: 'O Muadh, I love you. Do not forget to say this after every prayer.'