What are the conditions regarding agreements made during individual combat?

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If a Muslim warrior makes a condition with his opponent that no one else will assist him, the condition must be honored, for believers are bound by their agreements. If the Muslim fighter retreats due to injury or flees the fight, it becomes permissible for anyone to fight and kill him, as his engagement is concluded. If a condition was set that the Muslim would not be fought until he returned to his own line, this condition must be upheld unless he abandons the fight or is severely wounded, in which case pursuing and finishing him or preventing his rescue is permissible. If he resists that intervention, he forfeits his guarantee of safety and may be fought.