What is the exact source for this Hadith?

I was reading something when I came across this: The ruling of begging and when it’s obligatory to help a beggar; summarised from the words of Ibn Muflih (Died 763AH): The poor person (eligible for Zakāt) is the one who has a little bit extra over what suffices them or nothing at all according to the official Hanbalī and Shāfi’ī madhab. Whoever acquires wealth that isn’t gold or silver (currency) which doesn’t suffice him, then he is not rich, even if the value of what he acquires is alot. Whoever is unknown to you and says ‘I don’t have anything’, you are required to tell him it’s not permitted for a rich person to beg, and then afterwards one may give charity to him without asking this person to swear by Allāh (if he’s poor) according to all 4 madhabs due to the authentic hadīth. … Furthermore, informing him of this (i.e., that it’s not lawful to take money in such a situation) could be stated as obligatory, and this is the apparent words of the Hanbalī Imāms: ‘He gives him after informing him’, and this is in accordance with the Prophet’s actions (صلى الله عليه وسلم).“ So I’m just wondering where exactly this Hadith of telling a beggar that a rich man cannot beg is. Thank you very much