Sahih Bukhari 1427 — The wealthy only are required to give in charity

Narrated Hakim bin Hizam: The Prophet said, "The upper hand is better than the lower hand (i.e. he who gives in charity is better than him who takes it). One should start giving first to his dependents. And the best object of charity is that which is given by a wealthy person (from the money which is left after his expenses). And whoever abstains from asking others for some financial help, Allah will give him and save him from asking others, Allah will make him self-sufficient."