Is it permissible to work during the day in a pharmacy that sells narcotic drugs at night without a medical prescription, and is the income earned from this work lawful or unlawful?

It is not permissible to sell drugs that are used as narcotics, because that constitutes cooperation in sin and transgression, which is forbidden by Islamic law. The owner of the pharmacy must be advised to abandon this practice, and one should not assist him or be present at the time of their sale. If it is not possible to prevent the sale, then there is no harm in working in the pharmacy in permissible matters, and the earned wage is lawful. However, it is preferable to keep away from those who commit sins.