Illness appears on the face of it to be something very undesirable. But if you think about it deeply, you will discover that there is a positive aspect even in illness. It is said that whenever the Prophet visited a patient, he would say to him, “Don’t worry, God willing, it will be a means of purification.” (Sahih Bukhari, hadith no. 5656)
With regard to this hadith, the noted Hadith scholar Ibn Hajar says that the phrase “God willing” here proves that this saying of the Prophet is not to be taken in the sense of khabar, or a definite statement of fact, about sickness, but is rather a dua or supplication to God. But the fact is that this saying of the Prophet is a khabar in the form of a dua. This means that the sick person must develop positive thinking, and that in the face of illness, he must not yield to despair. In this prayer, there is a message of solace and comfort for people because in most cases, people recover from their illness.
In this way, the case of a sick person has a lesson to teach us about life in general. And that is that the system of this world is based on the principle of recovery. Here, if you lop off the branch of a tree, a new branch will begin to grow in just the same place. If a person falls sick, then, in line with the law of nature, he can regain his health. In this way, in this world, one can gain something that one has lost.
This principle of recovery after suffering a loss applies to every sort of loss that one may incur in life—economic loss, political loss, and so on. Hence, there is absolutely no place for complaint, no matter what the circumstances. This is an extremely important lesson for people, something that they can learn through personal experience in the event of illness.