Final answer:
Ruth's son was Obed, who fathered Jesse, who in turn fathered King David. Ruth stayed with Naomi out of profound loyalty and commitment.
Step-by-step explanation:
Ruth's son was the father of Obed, who became the father of Jesse in the Bible. A very important person born from this line is King David. The significant reason the daughter-in-law, Ruth, gave Naomi for staying with her is found in the Book of Ruth 1:16-17, where Ruth expresses loyalty to Naomi, saying, "Where you go I will go, and where you stay I will stay. Your people will be my people and your God my God." This statement reflects a profound commitment and love Ruth had for Naomi, transcending familial obligation.