Musnad Ahmad 1153:117

Sufyan narrated to us, Yahya narrated to us, from the nephew of ‘Amrah—and I do not know if it was this one or another—from ‘Amrah, who said: ‘Aishah fell ill, and her illness lasted a long time. A man came to Medina practicing medicine, so her nephews went to ask him about her ailment. He said: "By Allah, you are describing the symptoms of a woman who has been bewitched. This woman is bewitched; a slave girl of hers has bewitched her." She [‘Aishah] said: "Yes, she wanted me to die so that she would be set free." It was said that she was a *mudabbarah* (a slave promised freedom upon the master's death). She [‘Aishah] said: "Sell her to the harshest of the Arabs in ownership, and use the price of her to purchase the likes of her."