Ali bin Abu Talib reported,

On the day of Badr we captured two men, one from Quraysh and a freedman of Uqba bin Abu Muayt. As for the man from Quraysh, he escaped. As for the freedman of Uqba, we held him and began questioning him.We asked him, "How many are the people?"He replied, "By Allah, they are many in number and fierce in might."Whenever he said this, the Muslims would beat him, until they brought him to the Prophet ﷺ.The Prophet ﷺ asked, "How many are the people?"He answered, "By Allah, they are many in number and fierce in might."The Prophet ﷺ pressed him hard to tell him exactly how many they were, but he refused.Then the Prophet ﷺ asked him, "How many camels do they slaughter each day?"He said, "Ten every day."The Messenger of Allah ﷺ said, "The people are one thousand. Each camel feeds a hundred men and their followers."

عن علي قال

أخذنا رجلين يوم بدر رجلا من قريش، ومولى لعقبة بن أبي معيط، فأما القرشي فانفلت. وأما مولى عقبة فأخذناه فجعلنا نقول له: كم القوم؟ فيقول: هم والله كثير عددهم شديد بأسهم فجعل المسلمون إذا قال ذلك ضربوه، حتى انتهوا به إلى النبي ﷺ فقال: كم القوم؟ قال: هم والله كثير عددهم، شديد بأسهم، فجهد النبي ﷺ أن يخبره كم هم؟ فأبى، ثم إن النبي ﷺ سأله: كم ينحرون من الجزور؟ فقال: عشر كل يوم، فقال رسول الله ﷺ: القوم ألف كل جزور لمائة وتبعها.