Did our Nabi (Sallallahu alayhi wasallam) ever eat beef?

Answer

Yes, he did. Hadhrat Jaabir (Radhiyallahu anhu) narrated: "Rasulullah (Sallallahu alayhi wasallam) slaughtered a cow on the Day of Nahr (as Qur'baani) for Aishah (Radhiyallahu anha)." (Saheeh Muslim)

H a d h r a t A i s h a h (Radhiyallahu anha) narrated: "Beef was brought to the Nabi ( S a l l a l l a h u a l a y h i wasallam)." (Saheeh Muslim)