From Pope Benedict XVI's General Audience Catecheses on the Apostle Matthew. Image is from a study guide on the talks by Amy Welborn, available as a free download here.
Another reflection prompted by the Gospel narrative is that Matthew responds instantly to Jesus' call: "he rose and followed him". The brevity of the sentence clearly highlights Matthew's readiness in responding to the call. For him it meant leaving everything, especially what guaranteed him a reliable source of income, even if it was often unfair and dishonourable. Evidently, Matthew understood that familiarity with Jesus did not permit him to pursue activities of which God disapproved.
The application to the present day is easy to see: it is not permissible today either to be attached to things that are incompatible with the following of Jesus, as is the case with riches dishonestly achieved.
Jesus once said, mincing no words: "If you would be perfect, go, sell what you possess and give to the poor, and you will have treasure in heaven; and come, follow me" (Mt 19: 21).
This is exactly what Matthew did: he rose and followed him! In this "he rose", it is legitimate to read detachment from a sinful situation and at the same time, a conscious attachment to a new, upright life in communion with Jesus.