Victory through obedience to Allah

وَلَمَّا بَرَزُوا۟ لِجَالُوتَ وَجُنُودِهِۦ قَالُوا۟ رَبَّنَآ أَفْرِغْ عَلَيْنَا صَبْرًا وَثَبِّتْ أَقْدَامَنَا وَٱنصُرْنَا عَلَى ٱلْقَوْمِ ٱلْكَـٰفِرِينَ

And when they went forth to [face] Goliath and his soldiers, they said, "Our Lord, pour upon us patience and plant firmly our feet and give us victory over the disbelieving people."

فَهَزَمُوهُم بِإِذْنِ ٱللَّهِ وَقَتَلَ دَاوُۥدُ جَالُوتَ وَءَاتَىٰهُ ٱللَّهُ ٱلْمُلْكَ وَٱلْحِكْمَةَ وَعَلَّمَهُۥ مِمَّا يَشَآءُ ۗ وَلَوْلَا دَفْعُ ٱللَّهِ ٱلنَّاسَ بَعْضَهُم بِبَعْضٍ لَّفَسَدَتِ ٱلْأَرْضُ وَلَـٰكِنَّ ٱللَّهَ ذُو فَضْلٍ عَلَى ٱلْعَـٰلَمِينَ

So they defeated them by permission of Allāh, and David killed Goliath, and Allāh gave him the kingship and wisdom [i.e., prophethood] and taught him from that which He willed. And if it were not for Allāh checking [some] people by means of others, the earth would have been corrupted, but Allāh is the possessor of bounty for the worlds.