One criteria for charity giving

[Charity is] for the poor who have been restricted for the cause of Allah, unable to move about in the land. An ignorant [person] would think them self-sufficient because of their restraint, but you will know them by their [characteristic] sign. They do not ask people persistently [or at all]. And whatever you spend of good – indeed, Allah is Knowing of it.
Al Quran 2:273


What is Islam

He (again) said: Messenger of Allah ﷺ, (tell me) what does al-Islam signify. He (the Holy Prophet) replied:
Al-Islam signifies that you worship Allah and do not associate anything with Him and you establish obligatory prayer and you pay the obligatory poor-rate (Zakat) and you observe the fast of Ramadan.
– Sahih Muslim: Book 1 Hadith 5

Sahih Muslim, B1, H5_2