It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) gave his pure wives the choice between this world and the Hereafter, but he did not count it as a divorce, nor did he give them the right to divorce.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 588
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف محمد بن عبيدالله بن أبى رافع