In a report recorded by him, the words are: "Whoever recites these words at sunset:
'A'udhu bi-kalimatillahit-tammati min sharri ma khalaq' (I seek refuge in the perfect words of Allah Almighty from the evil of everything He has created).
The Prophet (peace and blessings be upon him) says: nothing will be able to harm that person during that night." Al-Tabarani recorded all these reports in al-Mu'jam al-Awsat; the first report contains a narrator, Muhammad bin Ibrahim, the brother of Abu Ma'mar, and I do not know him; the narrators of the last two reports are thiqat (trustworthy), though there is disagreement about some of them.
(Allamah al-Haythami says:) I say: The hadith narrated by Sayyiduna Anas (may Allah be pleased with him) will come later in the chapter on what a person should recite when a scorpion stings him and what he should recite when he goes to his bed.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 17025