Musnad Ahmad 1153:1496

Ishaq ibn Yusuf narrated to us, he said: Shareek narrated to us, from Ya'la ibn 'Ata, from al-Walid ibn 'Abd al-Rahman al-Jurashi, from 'Aisha, that she said: I menstruated while with the Messenger of Allah, peace and blessings of Allah be upon him, on his bed, so I slipped away. He said to me: "Have you menstruated?" I said: "Yes." He said: "Then fasten your lower garment upon yourself, then return."