Jesus sees Levi, a man no one trusts, sitting at his stand on the shore of Galilee and he says to him, "Come Follow Me." How could Jesus do such a thing? Tax collectors were lumped into the same category as murderers and theives.
And with that, Abraham packs up, gets his wife Sarah and nephew Lot ready, and they begin following God to the land of Canaan with everyone else.
When everyone else must have thought less of him, God was still calling him, and for David, this was worth his life. He knew he messed up and the Psalms are evidence of David’s longing for a clean heart and mind.