But what must I do? “Good teacher, what must I do to inherit eternal life?” 18 Jesus answered him, ….19 You know the commandments: ‘You shall not kill; you shall not commit adultery; you shall not steal; you shall not bear false witness; you shall not defraud; honor your father and your mother.’” 20 He replied and said to [Jesus], “Teacher, all of these I have observed from my youth.”
In responding more directly to the question, Jesus directs the man to the Law (especially Dt 30:15 and following; Ezekiel 33:15 as well) – the one who obeys the law will live. Other than “you shall not defraud” the list is straight from the Ten Commandments ((Ex. 20:12–16; Deut. 5:16–20) and covers one’s moral conduct in relationship with others – certainly one measure of a person’s reverence for God and obedience to his precepts. There is one measure of “goodness” for the inquirer – do you accept the will of God revealed in the Law?
It is with confidence that the man replies “Teacher, all of these I have observed from my youth.” Still, his question to Jesus suggests that behind a façade of security there was a heart which had lost much of its security and is now concerned with the dimensions of his own piety. Has he lost his joy and delight in God? Does he think that he now lacks the approval of God?
The Way Gets Harder. 21 Jesus, looking at him, loved him and said to him, “You are lacking in one thing. Go, sell what you have, and give to (the) poor and you will have treasure in heaven; then come, follow me.” 22 At that statement his face fell, and he went away sad, for he had many possessions.
Did you know that this is the only place in the gospels of Mark, Matthew, or Luke that Jesus is said to love (agapaō) someone. Then Jesus says, “give it all away and follow me.” When I have told Bible Study groups the uniqueness of this statement of love, it is not uncommon to hear a quip, “And this is love? I’ll take a pass.” It is said in jest, but…. all recognize that suddenly the high bar got very high.
Jesus notes that the man is “is lacking in one thing.” But what? We are not told; we can only infer from what follows. Is he unable to sell all his possessions? Is he unable to give to the poor? Note that Jesus doesn’t say that he has to give all that he had to the poor. Is he unable to leave his worldly life behind and come and follow Jesus? Is he unable to do what Jesus asks because he has “many possessions” or because he is too attached to those possessions? What constitutes “many possessions” rather than having just enough? Hard to say, but the command to sell his property and to distribute the proceeds to the poor pointed to new status among the poor the poor and helpless. Just the thought of that new status dramatizes the fact that man is helpless in his quest for eternal life.
Is this a general instruction for all? I would argue, no. It is addressed to this particular person in his wholeness of attitude and understanding about God’s will. Yet it is a demand for a piety that goes beyond the requirements of the Law. Lane  speculates that the “one thing he lacks is the self-sacrificing devotion which characterizes every true follower of Jesus… Jesus’ summons in this context means that true obedience to the Law is rendered ultimately in discipleship. This man will achieve the perfect observance of the Law when he surrenders himself and follows Jesus. Self-surrender implies a renunciation of his own achievement and the reception of messianic forgiveness through which a man is released to stand under the Law and to offer the obedience of love.”
…then come, follow me. The deepest answer to the question of v. 17, however, lies not in the command to sell all but in the call to follow Jesus. The command to follow Jesus is an invitation to lay hold of authentic life offered as a gift in his own person. Jesus’ demand is radical in character. He claims the man utterly and completely, and orders the removal of every other support which could interfere with an unconditional obedience. The terms defined by Jesus clarify what following signifies (cf. 10:28), and indicate that Jesus himself is the one answer to the man’s quest for life.
…and he went away sad, for he had many possessions. The response could not have been more vivid and instantaneous. His tragic decision to turn away reflects a greater love for his possessions than for life (cf. 4:19). The call of the Kingdom of God includes a demand for unyielding self-denial (cf. 8:34). Refusing the call only serves to accentuate the greatness of the renunciation demanded and the uniqueness of the Twelve as those who had abandoned everything in order to follow Jesus.
Mark 10:19 you know the commandments. Jesus responded by noting the second part of the Ten Commandments, which deals with human relationships (Exod 20:12–16; Deut 5:16–20), thus showing his commitment to the relational aspect of spiritual life. God desires a response that pursues righteousness. The reference to defrauding replaces the idea of coveting, and possibly concretizes that commandment. The fourth commandment comes last in this list, the only commandment listed that isn’t expressed negatively.
Mark 10:20 all of these I have observed from my youth. The rich man had no sense of lack, for he said that his record of obedience was unblemished. He had kept (lit., “guarded”) the commandments from his youth. He possibly anticipated affirmation, but Jesus had not finished with him yet.
Mark 10:21 Jesus loved for him. The text makes it clear that Jesus’ demand was rooted in his love for the man and in his awareness that he needed to redirect his life priorities.
sell what you have … follow me. The call to go and sell is expressed as an aorist imperative, which, in the Greek, calls for a single decisive act.
Mark 10:22 he went away sad, for he had many possessions. The man’s departure answers the questions. This is the first place in Mark’s narrative that we are told that the man was wealthy. He left because he could not respond positively to Jesus’ instruction. There is some question as to whether the man departed with sadness or anger, as the term stugnazō speaks of a face that falls and can refer to anger (Ezek 26:16; Dan 2:12; Wis 17:5), to being gloomy, or to being appalled (Ezek 27:35; 32:10), which may fit best here. His possessions meant more to him than serving others with what he owned and more than following Jesus to gain eternal life. The passage echoes 4:19 and 8:35–37. Affluence can be a real barrier to knowing God (France 2002:400–401).