Abū Bakr ‘Abdallāh bin Abī Quḥāfah aṣ-Ṣiddīq (; 573 CE – 23 August 634 CE) popularly known as Abu Bakr , was a senior companion (Sahabi) and—through his daughter Aisha—the father-in-law of the Islamic prophet Muhammad. Abu Bakr became the first openly declared Muslim outside Muhammad's family. Abu Bakr served as a trusted advisor to Muhammad. During Muhammad's lifetime, he was involved in several campaigns and treaties.