Is the agreed-upon wage due if a messenger carries a book to a distant city but finds the recipient absent and returns the book?

Primary text

The full agreed-upon wage is due for the messenger for both the journey there and the return journey. The wage for the outward journey is due because it was performed based on the explicit permission of the employer. The wage for the return journey is considered due through implied consent (*tadmeen*), as the implicit condition of the employer's command, if the recipient is absent, is that the book must be returned, because the alternative is its destruction, which the employer would not consent to. Therefore, returning it becomes the necessary action.