John Gill Commentary Luke 18:19

"And Jesus said unto him, Why callest thou me good? none is good, save one, [even] God." — Luke 18:19 (ASV)

And Jesus said to him
In answer to his question, beginning with the character he gave him:

why do you call me good ?
it being unusual to address men, even their Rabbins, under such a title:

none is good, save one, [that is], God :
or "but God alone"; as the Vulgate Latin and Arabic versions render it; or, "but the one God", as read the Syriac, Persic, and Ethiopic versions; (See Gill on Matthew 19:17).