Abu Dawud
Medicine
Book Number: 022 / Hadith Number: 3884
Narated By Abdullah ibn Amr ibn al-'As : The Apostle of Allah (pbuh) sued to teach them the following words in the case of alarm: I seek refuge in Allah's perfect words from His anger, the evil of His servants, the evil suggestions of the devils and their presence. Abdullah ibn Amr used to teach them to those of his children who had reached puberty, and he wrote them down (on some material) and hung on the child who had not reached puberty.