The Islamic Personality by Sheikh Taqīuddīn An-Nabahānī

The Islamic State may contract treaties of peace, truce, good neighbourliness, cultural treaties, commercial and financial treaties and treaties similar to these which the interests of the Islamic da’wah require according to the conditions consented to by Islam. If these treaties include conditions not consented by Islam, those conditions which are not correct in Islam are void and the rest of the treaty remains executed in the remaining conditions. This is because each condition contradicting the Shar’a is void even if the Muslims’ Khalifah was pleased with and agreed to it. If there was between the Islamic State and her enemy a situation of war, it is allowed for her to contract a truce and peace treaty with her according to what the situation requires at that time and what the interests of the da’wah require. If the Islamic State views that she should make peace and friendship with a neighbouring State or a State remote from her for a matter required for the interests of the da’wah, it is allowed for her to do this. The State may find in alliances with disbelievers a tool for the da’wah to reach them and to create a public opinion about Islam among them. There could also be the repelling of great evil through alliances or being able to reach another enemy. Therefore it is allowed for the Islamic State to contract good neighbourly treaties with neighbouring States just as it is allowed to contract non-aggression treaties with non-neighbouring States for a specific period if it sees in that a way for the Islamic da’wah, to protect Muslims or any benefit for Islam or Muslims or to conduct the Islamic da’wah. The Messenger (saw) did make a treaty with Banu Mudlij and Banu Dumrah to make safe the roads his army travelled upon and he made a treaty with Yuhanna bin Rub’ah in Tabuk to make safe the boundaries of the State in the direction of Rome in the boundaries of Bilad AsSham. If a people of the people of war request friendship for specific years for nothing, the Khalifah looks into that. If he sees it as good for Muslim due to their severe and great strength or for other than that, he can do this due to Allah’s statement:

And also because the Messenger (saw) made peace with the people of Makkah in the year of Hudaybiyya upon leaving war between them and him for a specified period. This was because it reached the Messenger (saw) that there was an accord between the people of Khayber and Makkah to invade Muslims, so he made peace with Quraysh then he went to fight Khayber. In all the allowed alliances, the command of contracting or not contracting them is left to the Khalifah’s opinion and ijtihad because the Khalifah is appointed as guardian and among guarding is firstly protecting the Muslims’ strength. He may view in the alliance benefit for Muslims if there is great strength in the disbelievers or he needs to make effort in the war homeland (Dar al Harb) to reach a people of great strength so he finds it necessary to make peace with those in his way. The issue is delegated to the Khalifah’ opinion to measure according to what he sees as good for Muslims, but if there is no good in the alliance for the Muslims then it is not necessary to make peace with them due to Allah’s statement:

And because fighting disbelievers is obligatory and leaving what is obligatory without excuse is not allowed. If a king or a leader or the State of the people of war seek a covenant (dhimmah) from Muslims on condition that he be left to rule in his kingdom in what he wills of killing, crucifying or anything else which is not suitable in Dar al-Islam, he is not responded to upon that as consenting to oppression when it is possible to prevent it is haram. And also because the dhimmi is the one who is compelled with the rules of Islam in what returns to transactions so this condition which the king or leader or the State presents is contrary to what the contract obliges and therefore it is void. So if peace or the covenant is given upon this, it is void from its conditions as they are contrary to Islam due to his (saw) saying:

If he requested peace or the dhimmah and is pleased with the rule of Islam, then the covenant falls to the Muslims so he is ruled by Islam and the land which he used to rule enters into the Islamic land. Defending it becomes defending the Islamic land and their support becomes obligatory like the support of the Muslims.