King James Version (KJV)
17 And when he was gone forth into the way, there came one running, and kneeled to him, and asked him, Good Master, what shall I do that I may inherit eternal life?
18 And Jesus said unto him, Why callest thou me good? there is none good but one, that is, God.
19 Thou knowest the commandments, Do not commit adultery, Do not kill, Do not steal, Do not bear false witness, Defraud not, Honour thy father and mother.
20 And he answered and said unto him, Master, all these have I observed from my youth.
21 Then Jesus beholding him loved him, and said unto him, One thing thou lackest: go thy way, sell whatsoever thou hast, and give to the poor, and thou shalt have treasure in heaven: and come, take up the cross, and follow me.
It would have been very simple for Jesus to simply say, "You need do nothing at all, your faith alone will save you." But He didn't.