John Gill 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)

Likewise I say unto you
As before, in (Luke 15:7)

there is joy in the presence of the angels of God ;
who are the friends and neighbours of Christ: (See Gill on Luke 15:6),

over one sinner that repenteth ;
which they have knowledge of, either by immediate revelation from God, or by observation in the church where they attend: the reason of this joy is, because there is one rescued out of the hands of Satan and his angels, between whom and them, there is an implacable enmity; and because another subject is added to Christ's kingdom, and by which it is enlarged, the prosperity of which they greatly desire; and because another heir is born in that family, to which they belong, and they have another social worshipper with them: and this joy is said to be "in the presence of" them; and so may design the joy of others, as of Father, Son, and Spirit, which is in their sight and knowledge; and also the joy there is among themselves.