Suppression is not the same as restraint

This distinction is the whole lesson, so it is worth being slow about.

Suppression is the face doing nothing while everything underneath carries on. It costs you a great deal, it does not reduce what you are feeling, and the other person usually knows anyway. It is the late, expensive move from lesson two.

Restraint in the sense the verse describes is a decision about what happens next. You are not pretending the anger is not there. You are declining to hand it the steering wheel, and then doing something, which in the verse is pardoning and doing good.

One of those is a performance. The other is an action. They look similar from outside for about five seconds, and then they stop looking similar at all.

Al-Ghazali draws the same distinction in the Ihya, and he draws it out of the verse's own wording. Ibn Qudamah makes the same observation in Mukhtasar Minhaj al-Qasidin.

وكذلك قال الله تعالى و الكاظمين الغيظ ولم يقل و الفاقدين الغيظ وهذا لأن العادة لا تنتهي إلى أن يجرح الإنسان فلا يتألم بل تنتهي إلى أن يصبر عليه ويحتمل وكما أن التألم بالجرح مقتضى طبع البدن فالتألم بأسباب الغضب طبع القلب ولا يمكن قلعه ولكن ضبطه وكظمه و العمل بخلاف مقتضاه فإنه يقتضي التشفي و الانتقام و المكافأة وترك العمل بمقتضاه ممكن

Our rendering: and likewise Allah said, those who restrain rage, and He did not say, those who lack rage. That is because habituation does not reach the point that a man is wounded and does not feel pain, but rather reaches the point that he bears it patiently and endures it. And just as feeling pain at a wound is what the nature of the body requires, so feeling pain at the causes of anger is the nature of the heart, and it cannot be uprooted, only governed and restrained, and acted against; for it demands satisfaction, revenge and requital, and leaving off acting on what it demands is possible.

Take the wound. Nobody trains themselves out of feeling a cut. What can be trained is what the hand does next. That is the whole of the distinction, and it accuses you of nothing.