The Prophet ﷺ said, and through another chain Habib bin Shaheed reported from Muhammad bin Sirin from Abu Hurairah from the Prophet ﷺ, "When a fly falls into the vessel of any of you, let him dip it in fully, for in one of its wings is disease and in the other is cure."Affan said on one occasion, "For one of its wings..."
حدثنا عفان حدثنا حماد يعني ابن سلمة قال أخبرنا ثمامة بن عبد الله بن أنس وقال عفان مرة قال زعم ذاك ثمامة
عن النبي ﷺ وعن حبيب بن الشهيد عن محمد بن سيرين عن أبي هريرة عن النبي ﷺ قال إذا وقع الذباب في إناء أحدكم فليغمسه فإن في أحد جناحيه داء والآخر دواء وقال عفان مرة فإن أحد جناحيه
Its isnad is sahih. Haythami graded it sahih in Majma 5/38, from the route of Bazzar. Bukhari narrated something similar 7/181, in the chapter on medicine, on the fly falling into a vessel, as did Abu Dawud 3/365 number 3844, in the chapter on foods, on the fly falling into food, and Nasai 7/179 number 4262, in the chapter on Fara and Atirah, on the fly falling into a vessel, and Ibn Khuzayma 1/56 number 105, in the chapter on purification, and it has already appeared at 7141.