Abu Hurairah reported that he accompanied the Messenger of Allah ﷺ when he visited a sick man suffering from a fever. The Messenger of Allah ﷺ said to him, "Receive glad tidings, for Allah says, 'This is My fire, which I impose upon My believing servant in this world so that it may be his share of the Fire in the Hereafter.'"
حدثنا أبو أسامة قال أخبرني عبد الرحمن بن يزيد بن جابر عن إسماعيل بن عبيد الله عن أبي صالح الأشعري
عن رسول الله ﷺ أنه عاد مريضا ومعه أبو هريرة من وعك كان به فقال له رسول الله ﷺ أبشر إن الله عز وجل يقول ناري أسلطها على عبدي المؤمن في الدنيا لتكون حظه من النار في الآخرة
Its isnad is sahih. Abu Usama is Hammad bin Usama the Hafiz, Abdul-Rahman bin Yazid bin Jabir is Abu Utba the Shami, Ismail bin Ubaydullah is the Makhzumi from Damascus, and Abu Salih the Ashari is the Shami, and they are all reliable narrators.The hadith was reported by Tirmidhi (4/412, no. 2088) in the chapter on Medicine, section 35, and by Hakim (1/245), who graded it sahih, and Dhahabi agreed with him.