Hasan bin Sa'd al-Juhani (may Allah have mercy on him) said: I asked Zayd bin Aslam (may Allah have mercy on him) about zakah. He said: Have you heard about Abdullah bin Umar (may Allah be pleased with them both)? I said: Yes. He said: He used to give it to them — meaning the ruler — during the time of turmoil (fitnah), and they would feed their animals with it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7384