It is narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) that he said: The Messenger of Allah (peace and blessings be upon him) said: "Write down for me the names of those among the people who have accepted Islam." So the names of one thousand five hundred men were written down for him (peace and blessings be upon him). I said: Do we fear while we are one thousand five hundred? Then I saw ourselves being tested, until a man among us would pray alone in fear. (b) It is narrated from al-A'mash: We found them to be five hundred.
(c) Abu Mu'awiyah said: They were between six hundred and seven hundred.
(61) Chapter: Giving the fay' according to the register (diwan), and with whom to begin
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 13069