O complaining sick person! Your right is to be grateful and patient, it is not to complain. For your body and members and faculties do not belong to you. You did not make them, and you did not buy them from other workshops. That means they are someone else’s property. Their owner has disposal over His property as He wishes.
As is stated in the Twenty-Sixth Word, an extremely wealthy and skilful craftsman, for example, employs a poor man as a model in order to show off his fine art and valuable wealth. In return for a wage, for a brief hour he clothes the poor man in a bejewelled and most skilfully wrought garment. He works it on him and gives it various states. In order to display the extraordinary varieties of his art, he cuts the garment, alters it, and lengthens and shortens it. Does the poor man working for a wage have the right to say to that craftsman: “You are causing me trouble and distress by making me bow down and stand up, and you are spoiling my beauty by altering this shirt which makes me beautiful,” and can he ever gain the right to say this? Can he tell him he is being unmerciful and unfair?
Just like this comparison, O sick person! The All-Glorious Maker (Sani’i Zuljalal) has bejewelled the garment of your body with luminous faculties like the eye, the ear, the reason, and the heart; and in order to display the embroideries of His Most Beautiful Names (Esma’ul Husna), He makes you revolve amid numerous states and changes you in many situations. Like you learn of His name of Provider (Razzaq) through hunger, you should also recognise His name of Healer (Shafi) through your illness. Since suffering and calamities show the decrees of some of His Divine names, there are many instances of good to be found within those flashes of wisdom and rays of mercy.
If the veil was lifted, you will find many pleasant and beautiful meanings behind this veil of illness which you fear and loathe.
Source: Twenty Fifth Flash: Fourth Remedy.