Casualties and Prisoners
Al-Bukhari lists Meccan losses as seventy dead and seventy captured.This would be 15%-16% of the Quraishi army, unless the actual number of Meccan troops present at Badr was significantly lower, in which case the percentage of troops lost would have been higher. 'Ali ibn Abu Talib alone accounted for 18 of the dead Meccans. Muslim losses are commonly listed at fourteen killed, about 4% of their engaged forces. Sources do not indicate the number of wounded on either side.
During the course of the fighting, the Muslims took a number of Meccan Quraish prisoner. Their fate sparked an immediate controversy in the Muslim army. There was no evidence of imprisonment, and in fact the prisoners were kept safe and catered for during that period. In the case of Umayyah, his former slave Bilal was so intent on killing him that his companions even stabbed one of the Muslims guarding Umayyah.
Shortly before he departed Badr, Muhammad also gave the order for over twenty of the dead Quraishis to be buried in the well at Badr. Multiple hadiths refer to this incident, which was apparently a major cause for outrage among the Quraish of Mecca. Shortly thereafter, several Muslims who had been recently captured by allies of the Meccans were brought into the city of Mecca and executed in revenge for the defeat.
According to the traditional blood feud (similar to Blood Law) any Meccans related to those killed at Badr would feel compelled to take vengeance against members of the tribe who had killed their relatives. On the Muslim side, there was also a heavy desire for vengeance, as they had been persecuted and tortured by the Quraishi Meccans for years. However, after the initial executions, the surviving prisoners were quartered with Muslim families in Medina and treated well, either as kin or as possible sources of ransom revenue.
Implications
The Battle of Badr was extremely influential in the rise of two men who would determine the course of history on the Arabian peninsula for the next century. The first was Muhammad, who was transformed overnight from a Meccan outcast into a major leader. Marshall Hodgson adds that Badr forced the other Arabs to "regard the Muslims as challengers and potential inheritors to the prestige and the political role of the [Quraish]." The victory at Badr also allowed Muhammad to consolidate his own position at Medina. Shortly thereafter he expelled the Banu Qaynuqa, one of the Jewish tribes at Medina that had been threatening his political position. At the same time Abd-Allah ibn Ubayy, Muhammad's chief opponent in Medina, found his own position seriously weakened. Henceforth, he would only be able to mount limited challenges to Muhammad.
The other major beneficiary of the Battle of Badr was Abu Sufyan. The death of Amr ibn Hashim, as well as many other Quraishi nobles gave Abu Sufyan the opportunity, almost by default, to become chief of the Quraish. As a result, when Muhammad marched into Mecca six years later, it was Abu Sufyan who helped negotiate its peaceful surrender. Abu Sufyan subsequently became a high-ranking official in the Muslim Empire, and his son Muawiya would later go on to found the Umayyad Caliphate.
In later days having fought at Badr became so significant that Ibn Ishaq included a complete name-by-name roster of the Muslim army in his biography of Muhammad. In many hadiths, individuals who fought at Badr are identified as such as a formality, and they may have even received a stipend in later years.The death of the last of the Badr veterans occurred during the First Islamic civil war.
As Paul K. Davis sums up, "Mohammed’s victory confirmed his authority as leader of Islam; by impressing local tribes that joined him, the expansion of Islam began."