(17) بَابُ إِذَا وَقَعَ الذُّبَابُ فِي شَرَابِ أَحَدِكُمْ فَلْيَغْمِسْهُ، فَإِنَّ فِي إِحْدَى جَنَاحَيْهِ دَاءً وَفِي الأُخْرَى شِفَاءً
Narrated Abu Huraira:
The Prophet (ﷺ) said "If a house fly falls in the drink of anyone of you, he should dip it (in the drink) and take it out, for one of its wings has a disease and the other has the cure for the disease."
Reference: Sahih al-Bukhari 3320
In-book reference: Book 59, Hadith 126
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 54, Hadith 537