Is a bequest concerning money the slave pays prematurely valid?

Primary text

A bequest concerning the money that the mukātab pays ahead of schedule (ta'ajjala) is valid, as it is a bequest conditional on a specific status. If the slave pays any amount prematurely, that payment belongs to the legatee. If the slave pays nothing prematurely and only pays upon the maturity of the installments, the bequest becomes void.