In The Name of Allaah, The Most Merciful The Bestower of Mercy
Imaam Ibnul Al-Jawzi (rahimahullaah) said:
Indeed, I see that when the majority of the people are stricken with illness, they would sometimes preoccupy themselves with (feelings) of anguish and complaining, and sometimes they would preoccupy themselves with medication. So preoccupation with the severity (of the illness) diverts them from the beneficial commandments, performance of good deeds or preparation for death. And how many (a person) has sins which he has not repented from, or trust which he has not returned, or a debt, or zakat (to pay), or a misdeed related to responsibility of his, which he has not realized! But his sadness is (focused) in his parting with the worldly life. He has no interest other than (the sadness felt due to parting with this world), and perhaps he may regain health and command wrong doing. The reason for this is due to weakness in Imaan, as Allaah (The Mighty and Majestic) said:
فَأَعۡرِضۡ عَن مَّن تَوَلَّىٰ عَن ذِكۡرِنَا وَلَمۡ يُرِدۡ إِلَّا ٱلۡحَيَوٰةَ ٱلدُّنۡيَا
ذَٲلِكَ مَبۡلَغُهُم مِّنَ ٱلۡعِلۡمِۚ
‘’Therefore withdraw (O Muhammad) from him who turns away from Our Reminder (this Qur’an) and desires nothing but the life of this world. That is what they could reach of knowledge.’’ [An-Najm: Ayah: 29-30]
Indeed, this is common amongst the majority of the creation, and we seek Allaah’s protection from being forsaken. Therefore, it is incumbent upon a cautious person that he is prepared when in a state of good health before a state of poor health.
Source: Ath-Thabaat Indal Mamaat: page:31