The permissible glance: It is to look with the corners of one's eyes without turning the neck; as narrated by Ibn Abbas (may Allah be pleased with him): "Indeed, the Messenger of Allah (peace be upon him) would glance during prayer to the right and left without turning his neck behind his back," in Al-Mu'jam Al-Kabir 11: 223, Sunan Al-Tirmidhi 2: 482, Sunan Al-Daraqutni 2: 83, and others. Ibn Al-Qattan authenticated it. See: I'laa Al-Sunan 5: 152. And Aisha (may Allah be pleased with her) said: "I asked the Messenger of Allah (peace be upon him) about looking around in prayer, and he said: It is a theft that the devil steals from the prayer of the servant," in Sahih Al-Bukhari 1: 261, and Sunan Al-Tirmidhi 2: 484. See: Al-Durr Al-Mukhtar 1: 433.