Lo! those who believed and left their homes and strove with their wealth and their lives for the cause of Allah, and those who took them in and helped them: these are protecting friends one of another. And those who believed but did not leave their homes, ye have no duty to protect them till they leave their homes; but if they seek help from you in the matter of religion then it is your duty to help (them) except against a folk between whom and you there is a treaty. Allah is Seer of what ye do.