اللّهُـمَّ أَعِـنِّي عَلـى ذِكْـرِكَ وَشُكْـرِك ، وَحُسْـنِ عِبـادَتِـك
Allāhumma ‘a`innī `alā dhikrika, wa shukrika, wa ḥusni `ibādatik.
O Allah, help me to remember You, to give You thanks, and to perform Your worship in the best manner.
Abu Dawud 2/86, An-Nasa'i 3/53. See also Al-Albani Sahih Abu Dawud 1 /284.