John Gill Commentary Luke 18:22

"And when Jesus heard it, he said unto him, One thing thou lackest yet: sell all that thou hast, and distribute unto the poor, and thou shalt have treasure in heaven: and come, follow me." — Luke 18:22 (ASV)

Now when Jesus heard these things
That he had kept all these commandments, and that ever since he was a child, and to that very time:

he said to him, yet you lack one thing ;
not but that he lacked many other things, and even every thing: for he had performed no one thing as it should be: but Christ said, partly in answer to his pert question, "what lack I yet?" and partly by an ironical concession, granting he had kept them all, as he had said, yet one thing was wanting; and chiefly with a view to mortify his pride and vanity:

sell all that you have, and distribute to the poor, and you
shall have treasure in heaven, and come and follow me ;
(See Gill on Matthew 19:21).