A:
The owner of the first truck must stop
transporting barley to Khamr manufacturers, as it is not permissible for the owner of the second truck to
carry empty bottles to the factories to be filled with Khamr. All this is considered a form of cooperation in sin and transgression, and Allah (Exalted be He) says:
...but do not help one another in sin and transgression.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.