George Haydock's Catholic Commentary
Psalms 39:18
Beggar. King David might assume this title, as well as all mankind. (St. Augustine) --- The same may be applied to Christ, according to his human nature, as the end of this psalm, and the following, belong to him, more than to David. (Calmet) --- He speaks in the name of penitents, whose sins he had undertaken to wash away. (Worthington) --- Careful. Hebrew, "will think of me." (Haydock) --- Slack. The faithful prayed for the coming of our Saviour, as they still entreat him to hasten the reward of the good. (Worthington)