Musnad Ahmad 1251:1

'Affan narrated to us, Wuhayb ibn Khalid narrated to us, he said: Muhammad ibn 'Ajlan narrated to us, from Ya'qub ibn 'Abdullah ibn al-Ashajj, from Sa'id ibn al-Musayyib, from Sa'd, from Khawlah bint Hakim, that the Prophet, peace and blessings of Allah be upon him, said: "If one of you, when he stops at a place, says: 'I seek refuge in the perfect words of Allah from the evil of what He created,' nothing in that place will harm him until he departs from it."