A summary of Works of Love - I make no claim to hold to anything written below, I'm only processing what I have read so for. I hope to write a couple blogs on my thoughts on the book soon though.
Kierkegaard starts this chapter by discussing "promises". A promise is not an honourable act because it is not an act at all, it is something that is in place of an act, it is a delayed act, but not itself an act. And it is certainly not anything good - it remains neutral until it is (un)fulfilled, then the act (or lack thereof) is judged. Therefore, Kierkegaard stresses that we should make no promises, we should simply act.
He then discusses the parable of the Father with the disobedient sons. One son says he will not do as he is asked (and does it anyways) and the other says he will do what he is asked (and doesn't do it). Kierkegaard insists that the son who says no is in a much better position than the son who says yes. Not because he chose to do what was asked of him, but because he made no attempt to deceive his father, while the "yes" son was deceiving his father and not doing the work promised. Therefore the "no" son is more likely to see his fault since he is more truthful.
Kierkegaard uses Romans 13:10 as his muse for the rest of the chapter: "Love is the Fulfilling of the Law". From here he makes some interesting observations, starting with Jesus' response to his questioners. He notices that, when someone tries to trap Jesus in a question, Jesus not only dodges the trap but also traps the questioner (into some kind of action) with his answer. The pharisee asks Jesus, "who is my neighbour" and Jesus tells a story that obliges the man to love everyone.
The law, for Kierkegaard is still active, but it has been fulfilled through Christ - therefore sections of it are irrelevant, but still active. He likens it to a sketch. The Law has been sketched out and Christ came and fulfilled (completed) it, it's now a complete picture. And what completes this sketch? Love. Where once there were only outlines, now there is vivid colour and detail. All thanks to Love. Therefore Love and the Law cannot be separated (how does one remove the sketch from the completely work?) and only the fool tries.