Proverbs 24:1-2 (ESV)
Be not envious of evil men,nor desire to be with them,
 for their hearts devise violence,
and their lips talk of trouble.
We are exhorted not to be envious of evil men. But why would we be tempted to envy the evil? Because of their power, success, wealth, and more. Their evil practises give them things that we would like to have. We live in a culture that honours the acquisition of money. To be sure, there are many laws that seek to protect people from those who would cheat, lie and steal to get the money of others, but that only amounts to saying that there are rules in place regarding how you are to acquire the most money you can. In any case, it is tempting to look at those who are successful, regardless of how they became so, and want what their work, legitimate or not, has given them.
This commandment is given because the Lord knows that no matter who we are or how sanctified we become, we are tempted to want to have what evil people have gained through evil means. To deny that we are so tempted is to open ourselves up for falling into the sin of desiring what evil people have gained for themselves and then being willing to do even as they did to gain it. Let us not skip over this necessary warning to us. To think that we will not fall into this sin is to be closer to it already than we think. The reason we are not to envy evil men is because their hearts devise violence and their lips talk of trouble.
But all that should not blind us to the personal application of this truth in this verse either. Christians must not want money, power etc. at the expense of their faithfulness to Christ. The call of Christ upon us is to follow Him no matter what the cost. This means, from this verse, that we will rather lose the money and the power than maintain or achieve it through evil or disobedient means. Better to be poor and faithful, than rich at the expense of our faith. Do not look at evil people with envy simply because they have money or other desirable things. They have wicked hearts who do not know Jesus Christ. Look at them with pity that because of their riches they are harder to convince of their need for Christ than others are and therefore their power is very short lived. Seek, through prayer and the delivery of the Gospel, to win them to your understanding of life rather than envy them for theirs. They are more needy than you are.