The book of Ruth is short, but gives some great examples of grace.

Ruth is a foreigner, apart from the people of Israel, apart from God.  Yet God graciously makes her part of his people, even including her as an ancestor of Jesus. She finds refuge in God.  In the same way, Peter tells us once we were not among God’s people, but now we are God’s people (2:9-10).  In Christ we have a relationship with God.  Ruth didn’t deserve it; neither do we.  But God made us his people and drew us to himself – that’s grace.

There is also the picture of the kinsman redeemer.  Boaz is a kinsman redeemer for Ruth – marrying her and providing for her.  Jesus is our kinsman redeemer – we are the bride of Christ, and he provides for us not only our daily needs but salvation as well.  Again, we don’t deserve this – it’s all grace.