Hazrat Abdullah bin Zaid bin Asim Mazni (may Allah be pleased with him) saw the Messenger of Allah (peace and blessings of Allah be upon him) lying on his back. He had placed one of his feet over the other.
Hadith Referenceاللؤلؤ والمرجان / كتاب اللباس والزينة / 1360
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 8 كتاب الصلاة: 85 باب الاستلقاء في المسجد ومد الرجل»
Brief Explanation
The prohibition of lying on one’s back with one leg placed over the other has also been mentioned. The prohibition applies in the case where there is a risk of the private parts becoming uncovered. If a person takes full care to cover the ‘awrah (private parts), then there is no objection to sleeping in this manner on one’s back. (Raaz)