اِذْ يُرِيْكَهُمُ اللّٰهُ فِيْ مَنَامِكَ قَلِيْلًاۗ وَلَوْ اَرٰىكَهُمْ كَثِيْرًا لَّفَشِلْتُمْ وَلَتَنَازَعْتُمْ فِى الْاَمْرِ وَلٰكِنَّ اللّٰهَ سَلَّمَۗ اِنَّهٗ عَلِيْمٌۢ بِذَاتِ الصُّدُوْرِ ( الأنفال: ٤٣ )
Iz yureekahumul laahu fee manaamika qaleela; wa law araakahum kaseeral lafashiltum wa latanaaza'tum fil amri wa laakinnal laaha sallam; innahoo 'aleemum bizaatis sudoor (al-ʾAnfāl 8:43)
[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. (Al-Anfal  : 43)
1 Mufti Taqi Usmani
(Recall) when in your dream, Allah showed them to you few in number. And if He had shown them to you many in number, you would have been demoralized and would have disputed in the matter, but Allah saved (you). Surely, Allah is fully aware of what lies in the hearts.