Hawzah News Agency – The commander of the faithful, Imam Ali peace be upon him says:

اغزُوهُم قَبلَ أنْ يَغزوكُم، فوَاللَّهِ ما غُزِيَ قَومٌ قَطُّ في عُقرِ دارِهِم إلّا ذَلُّوا، فتَواكَلتُم وتَخاذَلتُم حتّى‏ شُنَّت علَيكُمُ الغاراتُ، ومُلِكَت علَيكُمُ الأوطانُ.

'Invade them before they invade you, for by Allah, no sooner are a people invaded in their own homes than they are humiliated. So you were indifferent and treacherous towards each other until invasions were waged upon you, and your homelands were overtaken.'

Source: Nahj al-Balagha, Sermon 27