God does not look at your outward forms but at your hearts: the measure is inward
A saying of the Prophet moves the whole standard inside. Words can be arranged and postures can be held, and none of it reaches the place being weighed. Someone can pass every outward test while the part of them that counts never showed up.
Ḥuḍūr al-qalb: Presence of the heart
Al-Ghazali held that words said while the mind wanders barely count as worship. Anyone who has driven home and remembered none of the road knows how the mouth runs on its own. The same thing happens in prayer, and the person is elsewhere the entire time.
Ikhlāṣ: Sincerity
Sincerity means one audience only. The test arrives when nobody would ever find out: the same words, the same care, in an empty room. Hollow worship usually begins when a second listener slips in, and pleasing that listener quietly becomes the point.
Riyāʾ: Performing worship so that people see it
Al-Ghazali treats showing off as the quiet ruin of good acts. Showing off rarely announces itself; a person prays a little longer because someone walked in, and hardly registers the shift. Over years the habit hardens, until the act is aimed at the room and nowhere else.
Taqlīd: Holding a belief only because you were handed it
Taqlīd names belief carried on somebody else's say so. A person can inherit every rule, including whom to fear and when, without once having looked into any of it. The fear works as a habit, but it belongs to the people who taught it and never gets past the surface.
Dhawq: Tasting something for yourself
Sufis call firsthand knowing tasting, since hearing about honey and eating it are different things. Rules learned by heart can be recited flawlessly by someone who has felt nothing behind them. When the thing is finally met directly, the same old words come out carrying weight they never had before.