A.T. Robertson Commentary Luke 15:6

"And when he cometh home, he calleth together his friends and his neighbors, saying unto them, Rejoice with me, for I have found my sheep which was lost." — Luke 15:6 (ASV)

Rejoice with me (συνχαρητε μο). Second aorist passive of συνχαιρω, an old and common verb for mutual joy as in Php 2:17f. Joy demands fellowship. Same form in verse 9. So the shepherd

calls together (συνκαλε, note συν again) both his friends and his neighbours. This picture of the Good Shepherd has captured the eye of many artists through the ages.