Hakeemul Ummah Hazrat Moulana Ashraf Ali Thaanwi Sahib رحمه الله has said that it is stated in a Hadīth that there is reward for sickness as well. Many virtues of sickness have been narrated in the Ahādith. It is the general understanding that the reward for sickness is reliant on Sabr (patience). If the patient exercises Sabr, then he is rewarded for the sickness as well. There is a reward for the sickness as well as a reward for adopting Sabr. However, according to some Ulama, the reward for sickness is not reliant on Sabr. The two issues are separate. Even in the absence of Sabr, the person is still rewarded for the sickness.
(SOURCE: MALFOOZAAT OF HAZRAT MOULANA ASHRAF ALI THAANWI SAHIB رحمه الله, PART 6)