[Ruling on Leasing to (or Working for) One Who Trades in Narcotics]

Answer—with Allah is success: What appears to me is that it is permissible. This is indicated by the jurists’ statement that it is permissible to transact with an oppressor, buying and selling, except in what one knows to be the very object of injustice. If it is permissible to take his money in sales and purchases, then a fortiori it is permissible to carry it.
This is also indicated by the well-known dealings of the Prophet (May Allah bless him and his family and grant them peace) and the Muslims with the Jews in Medina—buying, selling, lending, and hiring; the Prophet (May Allah bless him and his family and grant them peace) died while his shield was pawned to a Jew for thirty ṣāʿs of barley.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2