17 Let not a Christian then murmur, let him see whose steps he follows: but if he loves good days, let him hearken unto Him teaching and saying, “Come, you children, hearken unto Me; I will teach you the fear of the Lord.” What would you? Life and good days. Hear, and do. “Keep your tongue from evil”. This do. I will not, says a miserable man, I will not keep my tongue from evil, and yet I desire life and good days. If a workman of yours should say to you, I indeed lay waste this vineyard, yet I require of you my reward; you brought me to the vineyard to lop and prune it, I cut away all the useful wood, I will cut short also the very trunks of the vines, that you have thereon nothing to gather, and when I have done this, you shall repay to me my labour.
Would you not call him mad? Would you not drive him from your house or ever he put his hand to the knife? Such are those men who would both do evil, and swear falsely, and speak blasphemy against God, and murmur, and defraud, and be drunken, and dispute, and commit adultery, and use charms, and consult diviners, and withal see good days. To such it is said, you can not doing ill seek a good reward. If you are unjust, shall God also be unjust? What shall I do, then? What do you desire? Life I desire, good days I desire. “Keep your tongue from evil, and your lips that they speak no guile,” that is, defraud not any, lie not to any.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)