Why did Sai Baba refuse to give a secret mantra or 'upadesh' to the woman who asked?

Sai Baba explained his refusal to give a secret mantra by sharing his own experience as a disciple. As he narrates in Chapter 19, despite serving his own Guru devotedly for twelve years, he never received a formal 'ear-mantra'. Instead, his Guru nurtured him through his powerful, loving gaze, similar to how a mother tortoise on one riverbank cares for her young on the other purely by sight. Baba directly tells the woman, "my Guru did not blow any mantra into my ears, so how can I blow one into yours?" He implies that true spiritual attainment comes from focused devotion and the Guru's grace, not from a secret instruction, advising her to simply "pay attention to me" for spiritual wealth.