Anas b. Mālik – Allāh be pleased with him – reports:

A female slave once entered upon ʿUmar b. Al-Khaṭṭāb – Allāh be pleased with him – and he recognised her as having been owned by some of the Muhājirūn or the Anṣār, but she was wearing a jilbāb covering her head with it, so he asked her, “Have you been freed?” To which she replied, “No.” So he said, “Then why the jilbāb? Remove it from your head, the jilbāb is only to be worn as a duty by the free women of the believers.” She hesitated and was slow to comply so he raised his stick and hit her on the head with it until she cast [the jilbāb] from her head.

Ibn Abī Shaybah, Al-Muṣannaf ḥadīth 6240. Graded ṣaḥīḥ according to the conditions of Muslim by Al-Albānī in Irwāʾ Al-Ġalīl 6:204.