Combing the Hair (Kitab Al-Tarajjul)
Dawud :: Book 33 : Hadith 4154
Narrated Aisha, Ummul Mu'minin:
A woman made a sign from behind a curtain to indicate that she had a letter for the Apostle of Allah (peace_be_upon_him). The Prophet (peace_be_upon_him) closed his hand, saying: I do not know this is a man's or a woman's hand. She said: No, a woman. He said: If you were a woman, you would make a difference to your nails, meaning with henna.