Neb. Rev. Stat. § 16-502

No officer shall receive any pay or perquisites from a city of the first class other than his or her salary, as provided by ordinance and the law relating to cities of the first class, and the city council shall not pay or appropriate any money or any valuable thing to any person not an officer for the performance of any act, service, or duty, the doing or performance of which shall come within the proper scope of the duties of any officer of such city, unless the money or valuable thing is specifically appropriated and ordered by a vote of three-fourths of all the members elected to the city council.