Volume 5 · Book 58 · Hadith 198
Narrated Abu Ishaq Saud bin Abi Waqqas: None embraced Islam, except on the day I embraced it. And for seven days I was one of the three persons who were Muslims (one-third of Islam).
— Sahih Bukhari, Volume 5, Book 58: Merits of the Helpers in Madinah (Ansaar), Hadith #198