Aum (also spelled om) is believed to comprise just about every vibration that has ever existed or will exist Sooner or later. It is also the energetic root of other, more time mantras. कामिनां बहु मन्तव्यं सङ्कल्पप्रभवोदयम् Historically, a teacher or spiritual chief could possibly provide a student a mantra https://www.youtube.com/@Mahavidyabaglamukhi