Inspired by my question "Why isn't it cow meat prohibited when it is said to cause sickness?" I ask this:
عليكم بألبان البقر و سمنانها ، و إياكم و لحومها ،فإن ألبانها و سمنانها دواء و شفاء ، و لحومها داء
... The milk of the cow contains healing, its fat is a medicine, and beware (iyyakum) of its meat, which causes sickness.
iyyakum mean in this hadith?
I am familiar with it to mean "Beware!". I.e iyyakum an tafa'alu hada! (beware of doing this!) In Arabic, iyyakum is used as a warning and prohibition, see here 1, 2, 3. But it seems it also might be used as a "nasiha, advice", according to the context. But in this context, it seems a bit hard to distinguish.
Then of course it also could mean "and to you" but that is not relevant in this context.