Is it permissible to stipulate permissible service or benefit as consideration in a Mukataba contract (a contract of manumission contingent on payment)?

Primary text

The stipulation of permissible service or benefit as consideration in a Mukataba contract is valid because it represents one of the two compensations in an Ijarah (lease/hire contract), thus it is permissible to serve as compensation in a Mukataba, similar to currency.