What is the secondary view regarding the voiding of a voluntary bequest if the designated person refuses the specific service?

Primary text

It is also held that the bequest is not voided, and another substitute is appointed, because the intent was for the act of seeking closeness to God (*qurbah*) coupled with designation. If the designation fails, the pursuit of closeness to God does not fail, similar to when a command to sell one's slave to a specific person for charity is not accepted by that person; the slave is then sold to someone else and the proceeds are given in charity.