The Prophet Muhammad ﷺ said: "If a fly falls into the vessel of any of you, let him dip it all in (the vessel) and then throw it away, for in one of its wings there is a disease and in the other there is a healing." (Narrated by Al-Bukhari, no. 3320, and Abu Dawud, no. 3844).
For centuries, this hadith was misunderstood. How could a fly, a vector of disease, carry a remedy?
Modern microbiology has revealed that the house fly (Musca domestica) indeed carries pathogens on its wings and body. Recent studies have shown that the fly possesses an antibacterial defense system: it produces antimicrobial peptides that neutralize the pathogenic bacteria it carries. By dipping the fly entirely into the liquid, these antibacterial substances are released and can counter the germs present.
Researchers have identified natural antibiotic compounds in fly secretions, capable of inhibiting the growth of dangerous bacteria. This discovery, made in the 20th century, confirms the wisdom contained in this prophetic hadith dating back fourteen centuries.