Based on the provided texts, what is the core lesson Sai Baba imparts about how one should worship him?

Sai Baba's core lesson on worship revolves around the principle of seeing him in all living beings. As recounted in Chapter 9, he explains this concept to a devotee by revealing his oneness with a hungry dog she had fed and a pig she had seen. Baba states, "Sometimes I am a dog, sometimes a pig; sometimes I am a cow, sometimes a cat. Sometimes as an ant, a fly, or aquatic creature, in such forms I roam." He emphasizes that the person he truly loves is the one who sees him in all beings. Therefore, he instructs his followers to renounce the sense of difference and separation, as this practice of recognizing the divine in every creature is the truest form of worshipping him.