The Messenger of Allah ﷺ sent me and said, "You are going to a people from among the People of the Book. Call them to bear witness that there is no god but Allah and that I am the Messenger of Allah ﷺ. If they obey you in that, then inform them that Allah has made obligatory upon them five prayers in every day and night. If they obey you in that, then inform them that Allah has made obligatory upon them a charity to be taken from their wealthy and given back to their poor. If they obey you in that, then beware of taking the most prized of their wealth, and guard yourself against the supplication of the wronged, for there is no barrier between it and Allah."
بعثني رسول الله ﷺ قال: إنك تأتى قوما من أهل الكتاب، فادعهم إلى شهادة أن لا إله إلا الله وأني رسول الله ﷺ. فإن هم أطاعوا لذلك فأعلمهم أن الله افترض عليهم خمس صلوات في كل يوم وليلة. فإن هم أطاعوا لذلك فأعلمهم أن الله افترض عليهم صدقة تؤخذ من أغنيائهم فترد في فقرائهم. فإن هم أطاعوا لذلك، فإياك وكرائم أموالهم. واتق دعوة المظلوم فإنه ليس بينها وبين الله حجاب.
Bukhari related it in the chapter on zakat (1458), and Muslim in the chapter on faith (19), both by way of Yahya bin Abdullah bin Sayfi, from Abu Mabad, from Ibn Abbas, who narrated it. The wording given is Muslim's.His words, "the choicest of their wealth" — karaim is the plural of karimah, which refers to that which combines all the excellence possible for it, whether abundance of milk, beauty of form, or plentifulness of meat or wool.