Imām ʿAbd al-Raḥmān ibn Nāṣir al-Saʿdī (d. 1376 AH) said: “[The difference between an individual with īmān and a person who is lacking it] is actualised through experience. If you were to contemplate and analyse the conditions of mankind, you would see a great difference between the example set by the muʾmin who acts in light of his īmān and a person who lacks [īmān]. This dīn encourages, to the highest degree, true satisfaction with the varieties of provision, bounties, and graciousness granted by Allāh.
So when tested with sickness, poverty, or some other [hardship] that can afflict any individual, the muʾmin will have comfort in his eyes because of his īmān, the satisfaction he possesses, and the pleasure he has with the provision of Allāh.
His heart does not try to seek that which he realises has not been ordained for him. He always looks at those who are less fortunate than he is, rather than those above him.
It is also possible that his delight, happiness, and calmness exceeds even the one who has been given every valuable thing in this worldly life. For [this person] may not hold satisfaction in his heart like the muʾmin.
You will also find that when the one who does not act according to his īmān is tested with poverty or the loss of some valuable commodity from this worldly life, his condition becomes abhorrent and he is full of sadness and depression.”