Psalm 15

David's Psalm 15 begins with a question, "Who shall dwell on your holy hill?"  The rest of the psalm is an answer, listing the qualities of a man which please God.

This person:

walks blamelessly
does what is right
speaks truth in his heart
does not slander with his tongue
does no evil to his neighbor
takes up no reproach against his friend
despises the vile
honors those who fear the Lord
swears to his own hurt and does not change
does not put out his money at interest
does not take a bribe from the innocent

From Spurgeon's Treasure of David:

"The question is raised, because it is a question. All men have not this privilege, nay, even among professors there are aliens from the commonwealth, who have no secret intercourse with God. On the grounds of law no mere man can dwell with God, for there is not one upon earth who answers to the just requirements mentioned in the succeeding verses."

"In perfection this holiness is found only in the Man of Sorrows, but in a measure it is wrought in all his people by the Holy Ghost."

"Let us betake ourselves to prayer and self-examination, for this Psalm is as fire for the gold, and as a furnace for silver. Can we endure its testing power?"