Abd-Allah ibn Ubayy (Arabic: عبد الله بن أبي بن سلول, died 631), also called Ibn Salul in reference to his grandmother, was a chief of the Arab tribe Banu Khazraj and one of the leading men of Medina (then known as Yathrib). Upon the arrival of Muhammad, Ibn Ubayy became a Muslim, but the sincerity of his conversion is disputed. Because of repeated conflicts with Muhammad, Islamic tradition has labelled him a munafiq (hypocrite) and "leader of the munafiqun".