Muhammad bin Bujayd al-Ansari (may Allah have mercy on him) narrates from his grandmother Hawwa (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Give to the one who asks, even if it is a burnt hoof."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7749