Luke chapter 10

20 However, do not rejoice that the spirits submit to you, but rejoice that your names are written in heaven. 

21 At that time Jesus, full of joy through the Holy Spirit,[...]

It's not often that Jesus's emotion was emphasized, especially his joy or happiness. By contrast, his negative emotions, such as anger, sorrow, compassion, etc. were expressed more often, which are often caused by the  hardness or weakness of men. Here, Jesus (finally) had joy. This joy was arisen by Holy Spirit and just followed his comment to disciples' joy. That is to say that, just as what he told disciples, the Lord in Heaven was rejoicing that his followers go and do what they have heard, and that the names of theirs were writtenn in Heaven. Our God is truely a God of compassion. Not only sorrowing for our sins, but also rejoicing at our goodness and our reward. Just as this verse moving me:

The LORD your God is with you, he is mighty to save. He will take great delight in you, he will quiet you with his love, he will rejoice over you with singing. (Zeph3.17)

So that we should also make effort to please him, to make him happy, right?