I imitated a man in front of the Prophet ﷺ, and he said, "It would not please me to imitate someone, even in exchange for such and such."She said, I then said, "Messenger of Allah, Safiyyah is a woman," and she gestured with her hand as if to indicate that she was short.He said, "You have spoken a word that, were it mixed with the water of the sea, would taint it."
حدثنا محمد بن بشار حدثنا يحيى بن سعيد وعبد الرحمن بن مهدي قالا حدثنا سفيان عن علي بن الأقمر عن أبي حذيفة وكان من أصحاب ابن مسعود
حكيت للنبي ﷺ رجلا فقال ما يسرني أني حكيت رجلا وأن لي كذا وكذا قالت فقلت يا رسول الله إن صفية امرأة وقالت بيدها هكذا كأنها تعني قصيرة فقال لقد مزجت بكلمة لو مزجت بها ماء البحر لمزج
Its isnad is sahih. Abu Dawud narrated it in the Book of Manners, chapter on backbiting, hadith no. 4875, from the hadith of Yahya Qattan through this route. Yahya Qattan's narration from Sufyan Thawri is taken to be based on direct hearing.