وَبِاللَّهِ الْعِصْمَةُ وَالتَّوْفِيقُ، وَاللَّهُ أَعْلَمُ بِالصَّوَابِ وَإِلَيْهِ الْمَرْجِعُ وَالْمَآبُ.
Protection and enablement belong to Allah; Allah knows best what is correct, and to Him is the return and final destination.
ʿIṣmah in this prayer refers to protection from error, and tawfīq to divine help in remaining on the right course. Knowing what is correct does not eliminate a person's need for Allah's help.
Allah knows best what is correct expresses humility, while to Him is the return recalls accountability before Allah in the Hereafter.