Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that when the Messenger of Allah (peace and blessings be upon him) sent Sayyiduna Mu'adh (may Allah be pleased with him) to Yemen, he said to him: "Behold, you are going to a people from among the People of the Book (Christians and Jews), so the first thing you should invite them to is the worship of Allah. When they recognize Allah (i.e., accept Islam), then inform them that Allah has made five prayers obligatory upon them during the day and night. When they perform them, then inform them that Allah has made zakat obligatory upon them, which is to be taken from their wealthy (those who possess the nisab) and distributed among their poor. When they accept that, then take zakat from them, but avoid taking their best possessions (as zakat)."