How is the concept of 'Nishkam' service related to a devotee's 'shraddha' and 'saburi'?

The provided text does not establish a direct relationship between 'Nishkam' service and the concepts of 'shraddha' and 'saburi', as the latter are not mentioned. However, Chapter 0 provides a clear definition of Nishkam service. It is described as service performed with a selfless mind, specifically for the purpose of achieving liberation from the world or freedom from the cycle of birth and death. This is contrasted with 'Kamya' service, which is undertaken for worldly prosperity or the removal of calamities. The text unequivocally states that Nishkam Guru service is always the superior path.