Musannaf Ibn Abi Shaybah 19 — What a man says when he finishes

Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) said: Whoever, after finishing his ablution, says: "O Allah, I declare Your purity and Your praise; I bear witness that there is no deity except You; I seek Your forgiveness and turn to You in repentance," a seal is placed upon his words, then these words are preserved beneath the Throne, and that seal will not be broken before the Day of Resurrection.