Encouragement to fight the Disbelievers, and some Benefits of fighting Them
Allah says;
أَلَا تُقَاتِلُونَ قَوْمًا نَّكَثُواْ أَيْمَانَهُمْ وَهَمُّواْ بِإِخْرَاجِ الرَّسُولِ
Will you not fight a people who have violated their oaths and intended to expel the Messenger,
These Ayat encourage, direct and recommend fighting against the idolators who break the terms of their covenants, those who tried to expel the Messenger from Makkah.
Allah said in other Ayat,
وَإِذْ يَمْكُرُ بِكَ الَّذِينَ كَفَرُواْ لِيُثْبِتُوكَ أَوْ يَقْتُلُوكَ أَوْ يُخْرِجُوكَ وَيَمْكُرُونَ وَيَمْكُرُ اللَّهُ وَاللَّهُ خَيْرُ الْمَـكِرِينَ
And (remember) when the disbelievers plotted against you to imprison you, or to kill you, or to expel you; they were plotting and Allah too was plotting; and Allah is the best of those who plot. (8;30)
يُخْرِجُونَ الرَّسُولَ وَإِيَّـكُمْ أَن تُوْمِنُواْ بِاللَّهِ رَبِّكُمْ
and have driven out the Messenger and yourselves (from your homeland) because you believe in Allah your Lord! (60;1)
and,
وَإِن كَادُواْ لَيَسْتَفِزُّونَكَ مِنَ الاٌّرْضِ لِيُخْرِجُوكَ مِنْهَا
And verily, they were about to frighten you so much as to drive you out from the land. (17;76)
Allah's statement,
وَهُم بَدَوُوكُمْ أَوَّلَ مَرَّةٍ
while they did attack you first,
refers to the battle of Badr when the idolators marched to protect their caravan. When they knew that their caravan escaped safely, they still went ahead with their intent to fight Muslims out of arrogance, as we mentioned before.
It was also said that these Ayat refer to the idolators breaking the peace agreement with Muslims and aiding Bani Bakr, their allies, against Khuza`ah, the ally of the Messenger of Allah. This is why the Messenger of Allah marched to Makkah in the year of the victory, thus conquering it, all thanks and praise is due to Allah.
Allah said,
أَتَخْشَوْنَهُمْ فَاللّهُ أَحَقُّ أَن تَخْشَوْهُ إِن كُنتُم مُّوُمِنِينَ
Do you fear them!
Allah has more right that you should fear Him if you are believers.
Allah says here, `Do not fear idolators, but fear Me instead, for I am worthy of being feared by the servants due to My might and punishment. In My Hand lies the matter; whatever I will occurs, and whatever I do not will does not occur.'
Allah next said, while ordering the believers and explaining the wisdom of ordaining Jihad against them, all the while able to destroy their enemies with a command from Him,
قَاتِلُوهُمْ يُعَذِّبْهُمُ اللّهُ بِأَيْدِيكُمْ وَيُخْزِهِمْ وَيَنصُرْكُمْ عَلَيْهِمْ وَيَشْفِ صُدُورَ قَوْمٍ مُّوْمِنِينَ