The first reading today (2 Samuel 11:1-10) tells of King David's weakest hour. He sees Bathsheba bathing and decides he simply must have her. This wouldn't be quite as much of a problem if she wasn't already married, for while men at this time could have many wives, women could only have one husband. So, he makes a plan to have her husband killed in battle. While the plan works, David ultimately realizes what he did was wrong and the corresponding Psalm for today tells of his sorrow and his contrition:
For I am well aware of my offenses,
my sin is constantly in mind.
Against you, you alone, I have sinned.
I have done what you see to be wrong,
that you may show your saving
justice when you pass sentence,
and your victory may appear when you give judgement,
remember, I was born guilty,
a sinner from the moment of conception.
But you delight in sincerity of heart,
and in secret you teach me wisdom.
Purify me with hyssop till I am clean,
wash me till I am whiter than snow.
God, create in me a clean heart,
renew within me a resolute spirit,
do not thrust me away from your presence,
do not take away from me your spirit of holiness.
Psalm 51:3-7, 10-11