The Ahdnama is a treaty between Sultan Mehmet II (Al-Fatih) and the Bosnian Franciscan Christians of the Catholic Church in 1463.
The Ahdnama is a clear and definitive historical record of the rights Islam gave to Christians living under its rule. The original Ahdnama is still kept to this day in the Franciscan Monastery in the vicinity of Fojnica, Bosnia-Hercegovina.
Sultan Mehmet al-Fatih’s great-great grandfather was Sultan Murad I who began the conquests to open up the Balkans to Islam. He is famous for defeating the Serbs at Kosovo field in 1389 and establishing the authority of Islam over Kosovo. Allah blessed Sultan Murad I with martyrdom (shahadah) in this battle.
Sultan Mehmet’s father Murad II fought the second battle of Kosovo and began the conquests to open Bosnia to Islam. Following in the footsteps of his father and great-great grandfather, Sultan Mehmet completed their good work and opened up the entire region to Islam.
Islam, as the final message for mankind established clear and detailed rules relating to the rights of all non-Muslims living under its rule.
The Messenger of Allah ﷺ said: “He who harms a person under covenant, or charged him more than he can, I will argue against him on the Day of Judgement.”[1]
The classical scholars of Islam also detailed the rights of Muslims towards the non-Muslim citizens known as dhimmi. The famous Maliki jurist, Shaha al-Deen al-Qarafi says, “The covenant of protection imposes upon us certain obligations toward the ahl al-dhimmah. They are our neighbours, under our shelter and protection upon the guarantee of Allah, His Messenger ﷺ, and the religion of Islam. Whoever violates these obligations against any one of them by so much as an abusive word, by slandering his reputation, or by doing him some injury or assisting in it, has breached the guarantee of Allah, His Messenger ﷺ, and the religion of Islam.”

A translation of the Ahdnama is below.
Ahdnama of the Fatih sultan Mehmet
Mehmet the son of Murat khan, always victorious!
The command of the honorable, sublime sultan’s sign and shining seal of the conqueror of the world is as follows:
I, the Sultan Mehmet – Khan inform all the world that the ones who possess this imperial edict, the Bosnian Franciscans, have got into my good graces, so i command:
let nobody bother or disturb those who are mentioned, not their churches. Let them dwell in peace in my empire. And let those who have become refugees be and safe. Let them return and let them settle down their monasteries without fear in all the countries of my empire.
Neither my royal highness, nor my viziers or employees, nor my servants, nor any of the citizens of my empire shall insult or disturb them. Let nobody attack insult or endanger neither their life or their property or the property of their church. Even if they bring somebody from abroad into my country, they are allowed to do so.
As, thus, I have graciously issued this imperial edict, hereby take my great oath.
In the name of the creator of the earth and heaven, the one who feeds all creatures, and in the name of the seven mustafas and our great messenger, and in the name of the sword I put, nobody shall do contrary to what has been written, as long as they are obedient and faithful to my command.
May 28th 1463
Notes
[1] Narrated by Yahya b. Adam in the book of Al-Kharaaj

