ah i remember the hadith,
when angel Jibreel [a.s] asked prophet sallalahu alaihi wasallam abt ihsan,
n asked Man ihsan,
n prophet sallalahu alaihi wasallam replied .....
pray as if u r seeing Allah else...remember allah is seeing u.

not the complete hadith, but a part of it,
expect someone to post the exact hadith wid reference :brother: