Verily, you are coming to a people among the people of the Book, so call them to Tawheed of Allah (testify there is no God but Allah and I am the Messenger of Allah). If they accept that, then teach them that Allah has obligated five prayers in each day and night. If they accept that, then teach them that Allah as obligated charity to be taken from the rich and given to the poor. If they accept that, beware not to take from the best of their wealth. Be on guard from the supplication of the oppressed, for there is no barrier between it and Allah.