How can a Muslim be among the pious (muttaqeen), among the awliya’ Allah (friends of Allah), and among His servants who have held firm to the straight path, and how can he attain Allah’s pleasure, and how can he be certain that these qualities have been realized within him?

A servant becomes one of Allah’s Awliya (saints/devout servants) and attains His pleasure by achieving faith and piety. This is done by performing what Allah has commanded and avoiding what He has forbidden. Allah is also pleased with His servant through faith and righteous deeds. The righteous servant does not know whether their deeds have been accepted or not, so they live between fear and hope. This is the characteristic of Allah's servants who give what they give while their hearts tremble, and they fear that their deeds may not be accepted from them.