Sayyiduna Ibn Mas'ud (may Allah be pleased with him) said, regarding the saying of Allah Almighty: "On the day of the criterion, the day when the two armies met" [Surah al-Anfal: 41]: "The battle of Badr took place after the seventeenth of Ramadan had passed."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9041