al-Ḥāfiẓ al-Bayhaqī (d. 458/1066) said:

The story of the ulcer of our shaykh, al-Ḥākim Abū ʿAbd Allāh, may God have mercy on him – is that his face developed an ulcer, and he treated it with various remedies, but it did not heal and remained for nearly a year. He then asked the esteemed Imām, Abū ʿUthmān al-Ṣābūnī, to supplicate for him in his Friday gathering. Abū ʿUthmān prayed for him, and many people said “āmīn.” The following Friday, a woman threw a note into the gathering, stating that she had returned home and earnestly prayed for al-Ḥākim Abū ʿAbd Allāh that night. In her dream, she saw the Messenger of Allah as if he were saying to her: “Tell Abū ʿAbd Allāh to provide water generously for the Muslims.”

The note was brought to al-Ḥākim Abū ʿAbd Allāh, who then arranged for water to be given in charity and reciting supplications to it. People began drinking from it, and within a week, he experienced complete healing, the ulcer disappeared, and his face returned to its original state. He then lived for many more years.

Shaykh Muqbil bin Hādī al-Wādiʿī:

To commence, this is my letter to the scholars, which I give in a state of illness – and for all you know it may be a source of my cure by the permission of Allah ﷻ. It has been mentioned in the biography of Muḥammad ibn Ismāʿīl al-Amīr that he had some sort of sickness — perhaps it was chronic diarrhoea, and so he came across a book [written] by the people of innovation and misguidance. He then burnt the book and used it as tinder to cook some food. He ate the food and consequently was cured with the permission of Allah ﷻ.

So I hope that this tape will be a cause of my cure – by the permission of Allah. And if Allah ﷻ takes my life away then it [should be] considered as my final testament…