(A) The Mayor and City Council shall have no power to appropriate, issue or draw any order or warrant on the City Treasurer for money, unless the same has been appropriated or ordered by ordinance, or the claim for the payment of which such order or warrant is issued has been allowed according to the provisions of § 34.04, and funds for the class or object out of which such claim is payable have been included in the adopted budget statement or transferred according to law.
(Neb. Rev. Stat. § 17-708)
(B) All warrants drawn upon the City Treasurer must be signed by the Mayor and countersigned by the City Clerk, stating the particular fund to which the same is chargeable, the person to whom payable and for what particular object. No money shall be otherwise paid than upon such warrants so drawn. Each warrant shall specify the amount included in the adopted budget statement for such fund upon which it is drawn and the amount already expended of such fund.
(Neb. Rev. Stat. § 17-711)