Silsilat al-Ahadith al-Sahihah

Abu Huraira (may Allah be pleased with him) reports that Abu al-Qasim (peace and blessings of Allah be upon him) said: "When a person is sitting in the shade and, due to the shade shrinking, part of his body comes under the sun and part remains in the shade, then he should get up from there."

A companion of the Messenger narrates that the Messenger of Allah (peace and blessings be upon him) forbade a man from sitting in such a way that part of his body is in the sun and part in the shade, and said: "This is the sitting of Satan."

Sayyiduna Qais bin Abu Hazim narrates from his father, he says: I was sitting in the sun, the Prophet (peace and blessings be upon him) saw me and said: "Sit in the shade."