Musannaf Ibn Abi Shaybah 39448 — The great Battle of Badr, how it came

Ubaydah al-Salmani states that on the day of Badr seventy of the polytheists were taken captive and seventy of the polytheists were killed. Then the Messenger of Allah (peace and blessings be upon him) gathered the Ansar and gave them a choice (concerning the captives), saying: "Whatever you wish (will be done). If you wish, you may kill them, and the same number of you will be killed. And if you wish, you may take ransom, so that you may gain strength by it in the way of Allah." The Ansar said: "O Messenger of Allah (peace and blessings be upon him), we will take the ransom, by which we will gain strength in the way of Allah, and let the same number of us be killed." The narrator said: So the same number of the Companions as of the disbelievers were killed on the day of Uhud.