Du'a for courage in battle

وَلَمَّا بَرَزُوا۟ لِجَالُوتَ وَجُنُودِهِۦ قَالُوا۟ رَبَّنَآ أَفْرِغْ عَلَيْنَا صَبْرًۭا وَثَبِّتْ أَقْدَامَنَا وَٱنصُرْنَا عَلَى ٱلْقَوْمِ ٱلْكَٰفِرِينَ

When they advanced to meet Goliath and his forces, they prayed: "Our Lord! Pour out constancy on us and make our steps firm: Help us against those that reject faith."

وَمَا كَانَ قَوْلَهُمْ إِلَّآ أَن قَالُوا۟ رَبَّنَا ٱغْفِرْ لَنَا ذُنُوبَنَا وَإِسْرَافَنَا فِىٓ أَمْرِنَا وَثَبِّتْ أَقْدَامَنَا وَٱنصُرْنَا عَلَى ٱلْقَوْمِ ٱلْكَٰفِرِينَ

All that they said was: "Our Lord! Forgive us our sins and anything We may have done that transgressed our duty: Establish our feet firmly, and help us against those that resist Faith."