According to al-Ghazālī, two people may perform the same action,

yet one is saved while the other is ruined.

The reason is intention (niyyah):

it can turn a small act into a great one,

or turn a great act into something empty.

Without purifying intention, ethics is only outward religiosity.

? Iḥyāʾ ʿUlūm al-Dīn, Book: Intention and Sincerity (al-Niyyah wa al-Ikhlāṣ)