Tafsir of Al Imran 3:123

(And Allah has already helped you at Badr) This is an explanation of what results from patience and piety, following the exposition of what resulted from their absence, or it is a discourse meant to necessitate reliance upon Allah the Exalted by reminding them of what necessitates it.

Badr, as Al-Sha'bi said, is a well belonging to a man from Juhaynah named Badr, and thus it was named after him. Al-Waqidi said it is the name of the location, and it is said to be the name of the valley. It was, as Ikrimah said, a trading site in the Pre-Islamic era. Qatadah said: Badr is a water source between Makkah and Al-Madinah where the Prophet (may Allah the Exalted grant him peace and blessings) and the polytheists met. It was the first battle the Prophet (may Allah the Exalted grant him peace and blessings) fought, and it took place on Friday, the seventeenth of the month of Ramadan, in the second year of the Hijrah. The ba (in bi-Badr) carries the meaning of "in," meaning: Allah helped you in Badr.

(While you were few and weak) This is a state (hal) of the object in (helped you). Adhilla is a plural of scarcity for dhalil (weak/lowly), and it was chosen over dhala'il to indicate their scarcity alongside their weakness. What is intended by it is a lack of equipment, not the well-known [meaning of] humiliation, so there is no difficulty—if we affirm it—in the Prophet (may Allah the Exalted grant him peace and blessings) being included in this address. It has also been said: there is no impediment to the well-known meaning being intended, and that it signifies (while you were weak) in the eyes of others, even if you were mighty in yourselves. Discussion regarding their number and the number of the polytheists at that time has already preceded.

(So fear Allah) by avoiding His disobedience and exercising patience in His obedience. He did not explicitly command patience here, as what preceded and what followed suffice, while also—as some have said—indicating the nobility and originality of piety, and that patience is among its necessary principles. In ordering [piety] immediately after reporting the victory, there is an intimation that their aforementioned victory was due to their piety.

The meaning of His saying: (that you may be grateful) is: that you may fulfill the gratitude for what He has bestowed upon you of victory—which was near at hand—by virtue of your piety toward Him. It is also possible that it is a metonymy or a metaphor for attaining another blessing that necessitates gratitude; as if it were said: "So fear Allah that you may attain a blessing from Allah the Exalted, and thus be grateful to Him for it." Thus, gratitude is placed in the position of the blessing (bestowal), because [piety] is its cause and that which prepares for it.