Sahih Ibn Khuzaymah

Abu Bakr Kinanah bin Na’eem narrates that I was sitting with Sayyiduna Qabeesah (may Allah be pleased with him) when people from his tribe came to him and asked for help for the marriage of one of their companions. He refused to give them anything. I said to him, “You are the chief of your tribe, why did you not give them some wealth?” He replied, “These people have asked me unjustly. If their companion were to rub his private part until it became dry (i.e., useless), that would be better for him than this question they have asked of me. Indeed, I heard the Messenger of Allah (peace and blessings be upon him) say: ‘Begging is only permissible for three types of people: one whose wealth has been destroyed by some calamity or disaster, so he may ask until he gets enough to sustain himself, then he should stop asking; and one who has taken upon himself blood money or compensation for reconciliation among his people, so he may ask until he gets what he needs, then he should stop asking; and a person about whom three wise men from his people swear by Allah that so-and-so has become truly poor and needy (then he may ask). Other than these, asking is forbidden, and the one who begs consumes what is unlawful.’”