Psalms 5:4

For thou art not a God that hath pleasure in wickedness - The psalmist here refers to a well-known and well-understood characteristic of the Divine Being, that he was holy and pure, and that he could not have any pleasure in furthering the designs of wicked men. This is said with reference to his enemies, who were thus wicked; and the idea is that God would not, and could not, consistently with his nature, further their designs. This is the ground of encouragement which he had to pray - that he was conscious that his own aims were right, and that his cause was just, and that God could not favor the cause of the ungodly. This is still, and always will be, a ground of encouragement in prayer. If we know that our cause is right, we may look to God to favor it; if a cause is wrong, we cannot look to him to interpose to advance it. Good men, therefore, pray; wicked men do not.

Neither shall evil dwell with thee - The same idea is here expressed in another form. If God should show favor to the wicked, it would seem as if he admitted them to his habitation, as we do our friends and those in whom we delight. But as God would not do this, the psalmist feels that it was proper for him to call upon Him to deliver him from wicked people.