To those who would be perfect in grace, Jesus shows how they may come to perfection, "Jesus said to him, If you will be perfect, go, and sell all that you have, and give to the poor." Mark the words; He did not say, "Go, and consume all you have"; but "Go, and sell"; and not some, as did Ananias and Sapphira, but All. And well He added, "that you have", for what we have are our lawful possessions. Those therefore that he justly possessed were to be sold; what had been gained unjustly were to be restored to those from whom they had been taken. And He did not say, give to your neighbors, nor to the rich, but to the poor.
Yet many who leave their riches do not then follow the Lord; and it is not sufficient for perfection that they despise money, unless they also follow the Savior, that unless having forsaken evil, they also do what is good. For it is easier to condemn the riches than our own behaviour; therefore it follows, "And come and follow me"; for he follows the Lord who is his imitator, and who walks in his steps. It follows, "And when the young man had heard these words, he went away sorrowful." This is the sorrow that leads to death. And the cause of his sorrow is added, "for he had great possessions", thorns, that is, and briars, which choked the holy seed of faith.
Catena Aurea (St. Thomas Aquinas)
St. Remigius of Auxerre
Commentariorum In Matthaeum (St. Rabanus Maurus)
Commentariorum In Evangelium Matthaei (St. Jerome)