Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) relates that a slave girl of Hafsah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), cast a spell of magic on her, and she herself confessed to it. Hafsah (may Allah be pleased with her) gave the order to Abd al-Rahman bin Zayd, and he killed her. Uthman (may Allah be pleased with him) expressed his displeasure at this. Then Abdullah (bin Umar) went to him and said: She had practised magic and had confessed to it herself. In fact, Uthman (may Allah be pleased with him) had expressed his displeasure because Hafsah (may Allah be pleased with her) had done this without the ruler's permission.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19607