From Sahih Bukhari (Hadith 3953):
Narrated Ibn `Abbas:On the day of the battle of Badr, the Prophet (ﷺ) said, "O Allah! I appeal to You (to fulfill) Your Covenant and Promise. O Allah! If Your Will is that none should worship You (then give victory to the pagans)." Then Abu Bakr took hold of him by the hand and said, "This is sufficient for you." The Prophet came out saying, "Their multitude will be put to flight and they will show their backs
Reference: Bukhari 3953