If a fly falls into the drink of any one of you, he should dip it (in the drink) and then remove it, for in one of its wings there is a disease and in the other there is cure

عن أبي هريرة رضي الله عنه مرفوعاً: «إذا وقع الذباب في شراب أحدكم فليغمسه، ثم لينزعه؛ فإن في أحد جناحيه داء، وفي الآخر شفاء». وفي رواية: «وإنه يتقي بجناحه الذي فيه الداء».

Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah’s peace and blessings be upon him) said: “If a fly falls into the drink of anyone of you, he should dip it (in the drink) and then remove it, for in one of its wings there is a disease and in the other there is cure.” Another narration adds: “It (the fly) protects itself with the wing that has the disease.”

Source · Narrated by Bukhari

From the Hadith Encyclopedia (hadeethenc.com).