Sahih al-Bukhari, Book 56, Hadith 266 (In-Book) ⓘ
Narrated Al-A`mash: "We (listed the Muslims and) found them five hundred." And Abu Muawiya said, "Between sixhundred to seven-hundred."
حَدَّثَنَا عَبْدَانُ، عَنْ أَبِي حَمْزَةَ، عَنِ الأَعْمَشِ، فَوَجَدْنَاهُمْ خَمْسَمِائَةٍ. قَالَ أَبُو مُعَاوِيَةَ مَا بَيْنَ سِتِّمِائَةٍ إِلَى سَبْعِمِائَةٍ.
also referenced under: Hadith 3060 (DarusSalam) & Volume 4, Book 52, Hadith 294 (USC-MSA)