This verse should be rendered, And as he was going forth ( ἐκπορευομένου αὐτοῦ)—that is, just as he was leaving the house—there ran one to him, and kneeled to him, and asked him. St. Matthew (Matthew 21:20) says that he was "a young man."
St. Luke (Luke 18:18) that he was "a ruler." He had apparently been waiting for our Lord, waylaying him, though with a good intention. He showed zeal—as soon as he saw Jesus he ran to him; and he showed reverence, for he kneeled down to him.
He wanted advice from one whom he must have heard of as a celebrated Teacher; and he wanted this counsel as a matter of great interest to himself. Good Master. This would be the ordinary and courteous mode of accosting a person professing to be a teacher, so as to conciliate his attention and interest.
What shall I do that I may inherit eternal life? It is as though he said, "Rabbi, I know thee to be good, both as a man and as a teacher, and a prophet, well able to teach me perfectly those things which are really good, and which lead to blessedness hereafter.
Tell me, therefore, What shall I do?" St. Matthew (Matthew 21:17) says, "What good thing ( τί ἀγαθὸν ποιήσω) shall I do that I may inherit eternal life?"