Narrated Jabir:
"The Messenger of Allah (ﷺ) prohibited that a man sleep on a terrace without something to obstruct him (so that he will not roll off and fall)." (JA)
English reference (JA): Vol. 5, Book 41, Hadith 2854 (JA)
Arabic reference (JA): Book 43, Hadith 3091 (JA)