What is the oldest thing recorded by the Koran? E.g. whom/when are the commandments given?

What I find interesting is that from what you said/what I read from your links (which is very little, mind you), love doesn't seem to be a central aspect?
Example:
you shall not kill - except in the course of justice (Koran).
vs
you shall not kill (Bible).
I know that the old testament is extremely brutal in some parts. The thing is, though, that to my understanding, the two commandments given by Jesus are the central aspect of Christianity. Is there such an equivalence of the two "central" commandments I mentioned?