Actions are only by their intentions: the inside decides the deed
A saying of the Prophet puts the whole weight of an act on the reason behind it. Someone can hand over something costly and still be serving himself, especially when he picked which part of the instruction to keep. The size of the offering counts for nothing next to why it was made.
Riyāʾ: doing your worship so people will see it
Al-Ghazali treats this as the crack running through devotion, since from outside it looks the same as the honest thing. A person keeps the loud, visible part of what he was asked and lets the quiet part go. He ends up performing for whoever is watching, and calls the performance faithfulness.
Ghurūr: being fooled about where you stand
Al-Ghazali gives a whole book to the man who is sure he is fine. Such a person has already built a story in which he did what was wanted, and he believes it before anyone else hears it. Correction bounces off him, because he answers with the same reasons that convinced him first.
Nafs al-ammāra: the self that keeps pushing you toward what it wants
The Quran names the part of a person that gives orders from inside. This part seldom asks for anything ugly. It asks for the softened version of an instruction, the one that leaves your own preference untouched, and it makes that feel like good sense.
Ikhlāṣ: sincerity
The word means doing something for one reason only, with nothing mixed in. Someone with it stops measuring how the act will look and attends to what was asked. That strips away a great deal, since most of the effort in an impressive act goes into the part nobody requested.
We hear and we obey: hearing finishes in doing
The Quran joins listening and doing in one breath, and the tradition repeats the phrase as a single motion. A person who hears and then decides has already placed himself above the one who spoke. The gap between the two words is where the negotiating starts, and someone who obeys never opens it.