Translation:

29. O ye who believe! if ye fear Allah He will grant you a criterion (to judge between right and wrong) remove from you (all) evil (that may afflict) you and forgive you: for Allah is the Lord of grace unbounded.

Notes (Tafseer)

1202. Cf. ii. 53 and ii. 185. The battle of Badr is called the Furqan in Muslim theology, because it was the first trial of strength by battle, in Islam, between the powers of good and evil. Evil was defeated, and those who had real faith were tested and sorted out from those who had not faith enough to follow the banner of Faith. See also viii. 41 and n. 1210.