Al-Anfal 8:43

إِذۡ يُرِيكَهُمُ ٱللَّهُ فِي مَنَامِكَ قَلِيلٗاۖ وَلَوۡ أَرَىٰكَهُمۡ كَثِيرٗا لَّفَشِلۡتُمۡ وَلَتَنَٰزَعۡتُمۡ فِي ٱلۡأَمۡرِ وَلَٰكِنَّ ٱللَّهَ سَلَّمَۚ إِنَّهُۥ عَلِيمُۢ بِذَاتِ ٱلصُّدُورِ 43

[Remember, O Muhammad], when Allah showed them to you in your dream as few; and if He had shown them to you as many, you [believers] would have lost courage and would have disputed in the matter [of whether to fight], but Allah saved [you from that]. Indeed, He is Knowing of that within the breasts