Musnad Ahmad 1153:1542

'Abd al-Rahman narrated to us, he said: I heard Sufyan narrating, he said: 'Ali ibn al-Aqmar narrated to us, from Abu Hudhayfah—and he was one of the companions of 'Abdullah, and Talhah used to narrate from him—from 'A'ishah, she said: "I mimicked a man to the Prophet, peace and blessings of Allah be upon him, and he said: 'It would not please me that I mimicked a man, and that I have such and such.' She said: So I said: 'O Messenger of Allah, indeed Safiyyah is a woman—and he gestured with his hand as if he meant short—so he said: 'You have uttered a word that, if it were mixed with the water of the sea, it would have tainted it.'"