The full quote goes as follows:

"All mankind is from Adam and Eve, an Arab has no superiority over a non-Arab nor a non-Arab has any superiority over an Arab; also a White has no superiority over a Black nor a Black has any superiority over a White except by piety and good action. Learn that every Muslim is a brother to every Muslim and that the Muslims constitute one brotherhood. Nothing shall be legitimate to a Muslim which belongs to a fellow Muslim unless it was given freely and willingly."

I suspected this because it seems strange to me that there would be a need to mention this in the sermon, as I figured that there wouldn't be a difference between Black people or White people at the time, but I haven't found a translation that doesn't contain this part.

So, why did Muhammad feel the need to make this distinction in the first place?

Thanks!