What is the ruling on working in affiliate marketing for digital products online – such as books and medicines – given the existence of reservations, such as some books containing temptations (fitan), or ignorance regarding the efficacy of the medicines being marketed?

It is permissible to promote a website for beneficial books and earn from it, as long as most of the books are permissible and beneficial. It is also permissible to promote the aforementioned medicines and earn from them, and there is no need to know their effectiveness; this is the concern of specialists. However, one must refrain from promoting them if their adulteration is known from a reliable source.