Why was the giving of Udi considered a form of supreme, joy-giving advice from a Guru?

The act of giving Udi can be seen as a form of 'casual speech' that is 'beneficial advice, supremely eternal and joy-giving,' as mentioned in the opening of Chapter 33. While the act seems simple, its underlying message is profound. The Udi serves as a constant, tangible reminder of life's impermanence and the transient nature of the physical body and world. By internalizing this lesson, a devotee is guided away from worldly attachments and towards the eternal truth that Brahman alone is real. This realization is the source of supreme and lasting joy, making the simple gift of ash a powerful teaching from the Guru.