Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "Whoever recites Surah al-Kahf will have light on the Day of Resurrection as great as the distance from his dwelling to Makkah; whoever recites its last ten verses, then even if the Dajjal emerges, he will not be able to harm him; and whoever, after performing ablution, recites these words: 'You are free from every imperfection, O Allah, and with Your praise (we affirm Your purity); there is no god besides You; I seek Your forgiveness and I repent to You' (the Prophet (peace and blessings be upon him) says:) these words will be written on a scroll and a seal will be placed on it, which will not be broken until the Day of Resurrection."
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and its narrators are the narrators of the Sahih, except that Imam al-Nasa'i (may Allah have mercy on him), after recording this narration in his book "al-Yawm wa al-Laylah", said: This is a mistake; what is correct is that
it is mawquf (stopping at the Companion). Then he recorded it via Sufyan al-Thawri and Ghundar, from Shu'bah, as a mawquf narration.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1231