Question: Nowadays there are sleeping bags which a person enters and zips and nothing remains outside of it except the head. Dos this enter into Ishtimalus-Samma’ [wrapping oneself in a garment such that his hands are not free and his private parts are exposed] ?
Answer: “This is not from Ishtimalus-Samma’ in which the private parts are exposed. This is because this person enters this bag and nothing remains outside of it except his head. However, if something were to frighten him, then it would be difficult upon him. [For example] if someone tried to steal [from him] or a snake encounters him quickly, something [word unclear] will occur. It is not from Ishtimalus-Samma’ because it involves exposing the private parts and this does not involve exposing the private parts. In it is something forbidden, which is if something were to happen [it will be difficult to prevent] and something may not occur. However, it is not from Ishtimalus-Samma’ at all.
[Sharh Sunan Ibn Majah no. 254]
Faisal Ibn Abdul Qaadir Ibn Hassan