I love the Old Testament book of Ruth. It is full of interest, shedding light on NT doctrines. When in Malawi, I found many of the background references needed no explanation. Listeners were familiar with the agricultural background, with the range of crops coming into harvest at different times; and with levirate marriages, where a man was required to marry the widow of his deceased relative. One pastor, who had hosted me, named Boaz, left corners of his land unharvested for the local poor to glean, and ended up marrying a lady who worked in his land; although she was called Miriam, not Ruth!
In chapter 1, Ruth makes the decision to follow Naomi to Bethlehem in Judah, leaving behind her family, with all its security. This was a costly decision, to leave behind all that was familiar to her. She chose to find shelter under the wings of the God of Naomi, the God of Israel.
In chapter 4, she is delivered again, this time from the claims of the law. The law is represented by the nearer kinsman, who had first legal claim over her (Lev 25.25-27). He was concerned lest his own estate be endangered (4.6). The law is inflexible and unforgiving and can only condemn.
Boaz, in contrast, brings grace. He represents Christ. Strictly, in marrying Ruth, a Moabitess, his own descendants would be excluded from the worship of God (Deut 23.3). Yet the great-grandson of Ruth, David, became king of Israel. Here is mercy triumphing over justice; grace over law.
There was a cost for Boaz, as his own reputation as a righteous man was at risk. How much more for Christ, as He was called ‘friend of sinners.’ He died for the powerless, the ungodly, for sinners, (Rom 5.6-8).