‘Amr b. Shu'aib, on his father’s authority, said that his grandfather reported Allah's Messenger ﷺ as saying that when anyone was alarmed while asleep he should say, “I seek refuge in Allah's perfect words from His anger, His punishment, the evil of His servants, the evil suggestions of the devils and their presence,” for they will not injure him. 'Abdallah b. ‘Amr used to teach them to those of his children who had reached puberty and those who had not. He wrote them down on some material (1) and hung the writing on the child’s neck. 1. The word is sakh which usually means a document. Abu Dawud and Tirmidhi transmitted it, this being Tirmidhi's wording.