The Messenger of Allah ﷺ said, "On one of the fly's wings is poison, and on the other is a cure. When it falls into food, dip it fully in, for it puts forward the poison and holds back the cure."
أن رسول الله ﷺ قال: في أحد جناحي الذباب سم، وفي الآخر شفاء، فإذا وقع في الطعام فامقلوه فيه، فإنه يقدم السم، ويؤخر الشفاء.
Nasai (4262), Ibn Majah (3504), and Ahmad (11643) narrated it, and Ibn Hibban (1247) graded it sahih. All of them narrated it through Ibn Abu Dhib, from Saeed bin Khalid, from Abu Salama, who said, "Abu Saeed narrated it to me," and then he related it. Some abbreviated it and did not mention the poison.Its chain of transmission is hasan because of Saeed bin Khalid bin Abdullah bin Qariz al-Kinani al-Madani, who is disputed. Nasai declared him daif while others rated him hasan. This is among the narrations in which he did not err, since there is an established basis for it in the hadith of Abu Hurairah.Some mentioned a story about Saeed bin Khalid, who said, "I went to see Abu Salama, and he brought us butter and a lump of dates. A fly fell into the food, so Abu Salama began dipping it in with his finger. I said, 'Uncle, what are you doing?' He said, 'Abu Saeed Khudri narrated to me from the Messenger of Allah ﷺ,'" and then he related the hadith. Ahmad mentioned it.Al-kutlah, with a damma followed by a sukun, means a compact lump of dates or the like.