Wikipedia
Mustaʾmīn (Arabic: مستأمن) is a historical Islamic classification for a non-Muslim foreigner (harbi; from Dar al-Harb, the House of War, i.e. non-Muslim governed territories) who only temporarily resides in Muslim lands ( Dar al-Islam) via a short-term safe-conduct (aman mu'aqqat) which affords the musta'min the protected status of dhimmis (non-Muslim subjects permanently living in a Muslim-ruled land) without having to pay the jizya. This would include merchants, messengers, and students and other groups that could be given an aman, or pledge of security. Foreign envoys and emissaries are automatically protected by aman. The imam is permitted to grant an aman to any number, including entire populations. Any private Muslim individual has the juridical competence to grant an aman to as many as ten who are otherwise denizens of the Dar al-Harb.