Rabi´a al-Adawiyya is an Islamic saint. She is believed to have lived from 717 to 801 AD in what is now Iraq. While a poor orphan she was captured by a slave trader who proceeded to sell her into slavery. As a slave she was kept busy with her household duties until night, but once night time released her from her chores she devoted herself to prayer, going without sleep to do so. One night her master caught sight of her absorbed in prayer; he was astonished to see a light miraculously appear over her head which illuminated the entire house. Terrified he went back to his room, where he sat in wonder till daybreak. At dawn he approached Rabi´a, told her what he had seen, and gave her her freedom. Once free she moved to the desert where she devoted herself to prayer. As her holiness became more widely known, numerous individuals beat a path to her door seeking her spiritual direction.
Source : http://www.digiserve.com/mystic/Muslim/Rabia/index.html