Jamieson, Fausset and Brown on Luke 15:2

2. murmured, saying, &c.--took it ill, were scandalized at Him, and insinuated (on the principle that a man is known by the company he keeps) that He must have some secret sympathy with their character. But oh, what a truth of unspeakable preciousness do their lips, as on other occasions, unconsciously utter., Now follow three parables representing the sinner: (1) in his stupidity; (2) as all-unconscious of his lost condition; (3) knowingly and willingly estranged from God [Bengel]. The first two set forth the seeking love of God; the last, His receiving love [Trench].