30 Concerning the robbers who were crucified with Him, it is written, And He was numbered with the transgressors. Both of them were before this transgressors, but one was so no longer. For the one was a transgressor to the end, stubborn against salvation; who, though his hands were fastened, smote with blasphemy by his tongue. When the Jews passing by wagged their heads, mocking the Crucified, and fulfilling what was written, When they looked on Me, they shaked their heads, he also reviled with them. But the other rebused the reviler; and it was to him the end of life and the beginning of restoration; the surrender of his soul a first share in salvation. And after rebuking the other, he says, Lord, remember me; for with You is my account. Heed not this man, for the eyes of his understanding are blinded; but remember me. I say not, remember my works, for of these I am afraid. Every man has a feeling for his fellow-traveller; I am travelling with You towards death; remember me, Your fellow-wayfarer. I say not, Remember me now, but, when You come in Your kingdom.
Source: Catechetical Lectures (New Advent)