Musnad Abu Ya'la al-Mawsili 42:61

Zahmūyah narrated to us, Hushaym narrated to us, from Yaḥyā ibn Sa‘īd, from ‘Abd Allāh ibn Fulān al-Anṣārī, from his father, from Abū Sa‘īd, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "There is no zakat on less than five awāq (of silver), and there is no zakat on less than five camels (dhawd), and there is no zakat on less than five awsuq (of crops)." And the wasq is sixty ṣā‘s.