Musannaf Ibn Abi Shayba 28:479

Waki’ narrated to us, from Talha bin Yahya, that Umar bin Abdul Aziz used to send mail. A freed slave of his carried a man on the mail [service] without his permission. He said: So he summoned him and said, "He shall not marry until we value him, then we shall place him in the public treasury (Bayt al-Mal)."