Prophet Muhammad (Peace and Blessings be upon him) sent Mu’adh ibn Jabal to Yemen he told him,
“You will be going to Christians and Jews, so the first thing you should invite them to is the assertion of the oneness of Allah, Most High. If they realize that, then inform them that Allah (Subhan Wa Ta’ala) has made five obligatory prayers on them. If they pray them, then inform them that Allah has made the payment of charity from their wealth obligatory on their rich to be given to the poor. If they accept that, then take it from them and avoid the best part of people’s charity.”
~ Sahih Al Bukhaari ~