Final answer:
The reference materials don't specify the size of the Quraysh army at the Battle of Badr, but historical sources indicate it was around 900 to 1,000 men.
Step-by-step explanation:
The size of the Quraysh army in the Battle of Badr, which occurred in 624 CE, is not explicitly mentioned in the provided reference material concerning the general historical outline of Arab military campaigns and growth of the Islamic state. However, historical sources outside of the provided material suggest that the Quraysh army was composed of around 900 to 1,000 men at the Battle of Badr, a key battle that took place during the lifetime of the Prophet Muhammad. The provided material does discuss the overall capabilities of the Arab armies, their ability to field large numbers of troops, and the expansion efforts during the time following the Prophet Muhammad's passing, emphasizing their military strategy, tactics, and the importance of mobility.