Question of eternal life

Mark 10:17 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? Matt 19:16 And, behold, one came and said unto him, Good Master, what good thing shall I do, that I may have eternal life? Luke 18:18 And a certain ruler asked him, saying, Good Master, what shall I do to inherit eternal life?
Mark 10:18 And Jesus said unto him, Why callest thou me good? there is none good but one, that is, God. Matt 19:17a And he said unto him, Why callest thou me good? there is none good but one, that is, God: Luke 18:19 And Jesus said unto him, Why callest thou me good? none is good, save one, that is, God.
Mark 10:19 [1] 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. Matt 19:17b but if thou wilt enter into life, keep the commandments. 18 He saith unto him, Which? Jesus said, Thou shalt do no murder, Thou shalt not commit adultery, Thou shalt not steal, Thou shalt not bear false witness, 19 Honour thy father and thy mother: and, Thou shalt love thy neighbour as thyself. Luke 18:20 Thou knowest the commandments, Do not commit adultery, Do not kill, Do not steal, Do not bear false witness, Honour thy father and thy mother.
Mark 10:20 And he answered and said unto him, Master, all these have I observed from my youth. Matt 19:20 The young man saith unto him, All these things have I kept from my youth up [2]: what lack I yet? Luke 18:21 And he said, All these have I kept from my youth up.
Mark 10:21 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. Matt 19:21 Jesus said unto him, If thou wilt be perfect, go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me. Luke 18:22 Now when Jesus heard these things, he said unto him, Yet lackest thou one thing: sell all that thou hast, and distribute unto the poor, and thou shalt have treasure in heaven: and come, follow me.
Mark 10:22 And he was sad at that saying, and went away grieved: for he had great possessions. Matt 19:22 But when the young man heard that saying, he went away sorrowful: for he had great possessions. Luke 18:23 And when he heard this, he was very sorrowful: for he was very rich.

[1]It is instructive to compare Jesus' various lists of commandments to those in the old testament:

Exodus 20:3-17 Mark Matthew Luke
No other gods before the Lord      
No graven images      
Do not swear      
Remember the Sabbath      
Honor thy father and mother 6 5 5
Do not kill 2 1 2
Do not commit adultery 1 2 1
Do not steal 3 3 3
Do not lie 4 4 4
Do not covet      
(Do not defraud)* 5    
(Love your neighbor)*   6  

*Does not appear in Exodus' ten commandments.

[2]The phrase "from my youth up" is not in the original Greek of Matthew (Interpreter's One-Volume Commentary, p. 662 and The New Greek English Interlinear New Testament p. 73).