What is the meaning of ishtimal al-samma' in prayer? How is it done, and what is its ruling?

The Messenger of Allah forbade two ways of dressing: al-ihtiba' (sitting with knees drawn up) in a single garment without covering one's private parts, and ishtimal as-Samma' (enveloping oneself completely), which is to cover one's body entirely with a garment without lifting any part of it or extending one's hand out. It also includes lifting the garment from one side and placing it on one's shoulders, thus exposing one's awrah (private parts), or wearing a single garment draped over one shoulder such that it might reveal the awrah, or placing a cloak over one's head and letting its ends hang down to one's feet. These forms of dress contravene the words of Allah Almighty: {O Children of Adam, take your adornment at every masjid.}