A.T. Robertson Commentary Luke 15:10

"Even so, I say unto you, there is joy in the presence of the angels of God over one sinner that repenteth." — Luke 15:10 (ASV)

There is joy (γινετα χαρα). More exactly, joy arises. Futuristic present of γινομα (cf. εστα in verse 7).

In the presence of the angels of God (ενωπιον των αγγελων του θεου). That is to say, the joy of God himself. The angels are in a sense the neighbours of God.