Details of the truce in Islamic law. Here is a passage from Umdat al-Salik (Reliance of the Traveller), a Shafi'i Sharia manual endorsed by Al-Azhar University in Cairo as conforming to the "practice and faith of the orthodox Sunni community":
Truces are permissible, not obligatory....Interests that justify making a truce are such things as Muslim weakness because of lack of numbers or materiel, or the hope of an enemy becoming Muslim...If the Muslims are weak, a truce may be made for ten years if necessary, for the Prophet (may Allah bless him and give him peace) made a truce with the Quraysh for that long, as is related by Abu Dawud....The rulings of such a truce are inferable from those of the non-Muslim poll tax; namely, that when a valid truce has been effected, no harm may be done to non-Muslims until it expires. -- Umdat al-Salik, o9.16