A woman made a sign from behind a curtain to indicate that she had a letter for the Messenger of Allah ﷺ. The Prophet ﷺ 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. (Using translation from Abū Dāʾūd 4166)
مَدَّتْ امْرَأَةٌ مِنْ وَرَاءِ السِّتْرِ بِيَدِهَا كِتَابًا إِلَى رَسُولِ اللهِ ﷺ فَقَبَضَ النَّبِيُّ ﷺ يَدَهُ وَقَالَ مَا أَدْرِي أَيَدُ رَجُلٍ أَوْ يَدُ امْرَأَةٍ؟ فَقَالَتْ بَلْ امْرَأَةٌ فَقَالَ لَوْ كُنْتِ امْرَأَةً غَيَّرْتِ أَظْفَارَكِ بِالْحِنَّاءِ