Islamic states must abide by the agreements and treaties that they have acknowledged and entered into of their own accord; standing firmly with the international community towards achieving global peace and security [only] to the extent of the commitment of the signatory countries. Allah says:"O you who believe, fulfill [all] contracts " (5:1)
In the above verse, the term 'contract' refers to all commitments between two parties on a particular issue. In his interpretation of the above verse, the erudite Tunisian scholar, ibn 'Ashur says: "Contracts" in this verse refers to one of a genus denoting the totality [of contracts]. It includes covenants that Muslims made with their Lord such as to follow the shari'ah; pacts of allegiance between the believers and the prophet, peace and blessings be upon him, not to associate partners with Allah, steal, or commit fornication; agreements between Muslims and non-Muslims; and agreements between one Muslim and another" [Al-Tahriir wa al-Tanwir, 6/74].
Amr ibn Awf al-Muzna, may Allah be pleased with him, narrates that the prophet, peace and blessings be upon him, said: "Muslims are bound by the conditions [they stipulate] except those that are unlawful or those that make unlawful matters lawful." [reported by al-Tirmidhi].
Commenting on this hadith, al-Jass said: "It is a general obligation to fulfill all the conditions man holds himself to as long as there is nothing (in Islamic law) to restrict them." [Ahkam al-Qur`an, 2/418].
Ali, may Allah be pleased with him, narrated that the Prophet, peace and blessings be upon him, said: "The protection granted by the weakest Muslim to a non-Muslim is tantamount to that of the entire [community]. Whosoever violates it incurs the curse of Allah, the angels, and all the people." [Reported by al-Bukhari].
Abdullah ibn Umar, may Allah be pleased with them both, narrated that the Prophet, peace and blessings be upon him, said: "The signs of hypocrisy are four: when he is entrusted with something he betrays the trust, when he speaks he lies, when he makes a promise he breaks it, when he quarrels he behaves in an immoral manner. Whoever possesses all four is a hypocrite and whoever possesses one of them possesses an element of hypocrisy until he gives it up." [Reported by al-Bukhari in his Sahih].
Umar ibn al-Hamq al-Khazai narrated that the Prophet, peace and blessings be upon him, said: "If a man entrusts another with his life and is killed by him, I have nothing to do with the murderer, even if the murdered man were a non-Muslim."