A demon who casts doubt at the time of prayer. ‘Usman ibn Abi ‘l-Asi relates that he came to the Prophet and complained that he was disturbed by the devil during prayers. The Prophet said, “This is a demon called Khanzab who disturbs prayer. When you are aware of any such disturbances, seek protection of God and spit over your left shoulder three times.” ‘Usman did so, and all doubt and perplexity was dispelled.
Based on Hughes, Dictionary of Islam