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‘Uqba b. ‘Amir told that he heard God's Messenger say when he was on the pulpit, “Prepare for them as much strength as you can. Strength is shooting; strength is shooting; strength is shooting.” Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
عَن عُقْبَةَ بْنِ عَامِرٍ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَهُوَ عَلَى الْمِنْبَرِ يَقُول: " (وَأَعدُّوا لَهُ مَا استطَعْتُمْ منْ قُوَّةٍ) أَلَا إِنَّ الْقُوَّةَ الرَّمْيُ أَلَا إِنَّ الْقُوَّةَ الرَّمْيُ أَلَا إِنَّ الْقُوَّةَ الرَّمْيُ) رَوَاهُ مُسْلِمٌ
sunnah.com