Abu Amr bin Himas narrates that his father passed by Umar bin al-Khattab (may Allah be pleased with him). He said: There was leather on my neck, and Umar (may Allah be pleased with him) said: Do you pay its zakah? I said: O Commander of the Believers, I have nothing besides this which is on my back and what I have put to tan in the bark. He said: This is wealth; put it down. He said: So I put it down in front of him. He assessed it and found that zakah had become due on it, and then he collected the zakah from it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7603