Which specific teaching, in the form of a repeated phrase, did Maharaj tell the author he adopted after he stopped giving medicine?

In a conversation with the author (whom he called "Kaka"), Maharaj explained the spiritual practice he undertook after he stopped administering medicine. As recounted in the introduction of Chapter 0, Maharaj stated, "Later, I stopped giving medicine and started saying 'Hari Hari'." He then revealed the profound result of this practice by adding, "and while saying Hari Hari, I met Hari." This simple yet powerful teaching highlights a shift from physical remedies to a path of devotion and name-repetition as his means for both self-realization and helping others.