سورة Al-Imran ( The Famiy of Imran ) - الآية 165

And how come when a calamity befell you, you began to ask: 'How has this come about?' even though the enemy has suffered at your hands (in the Battle of Badr) double what you have suffered! Say: This calamity has been brought about by yourselves. Surely Allah is Ail-Powerful.