Cundī dhāraṇī or mantra also to start with appeared inside the Kāraṇḍavyūhasūtra: namaḥ saptānāṃ samyaksaṃbuddha koṭīnāṃ tadyathā oṃ cale cule cunde svāhā The use of mantra or even the repetition of selected phrases in Pali is really a remarkably typical method of meditation in the Theravada tradition. Very simple mantras https://www.youtube.com/@AacharyaGoldieMadan/