Based on Chapter 25, describe Damu Anna's background and his specific devotional practice related to the Ram Navami festival.

Chapter 25 provides several key details about Damu Anna. He was a wealthy Kasar, or bronze-smith, from Ahmednagar and was known to be a person devoted to Sai's feet. The chapter highlights his devotional practice tied to the annual Ram Navami festival in Shirdi. For many years, he maintained a vow to provide one of the two large flags for the festival procession, a practice he upheld with great love and devotion. The other flag was from the Nimonkars. The text also mentions a personal trial he overcame with Sai's grace: despite having two wives, he was childless until Sai's blessings granted him sons.