The Prophet ﷺ said, "None of you should lie on his back and then place one leg over the other."
أن النبي ﷺ قال: لا يستلقين أحدكم ثم يضع إحدى رجليه على الأخرى.
Muslim narrated it in the Book of Dress (2099:74), from Ishaq bin Mansur, who reported to us from Rawh bin Ubada, who narrated to me from Ubaydullah, meaning the son of Akhnas, from Abu Zubayr, from Jabir bin Abdullah, who mentioned it.