It is not very well known that Shri Ramakrishna gave the teaching of core Advaita to someone who asked him to give very crisp teaching by which he could get enlightened. Sri Ramakrishna said 'Brahma Satyam Jagat Mithya. Contemplate this.'
This incident has been recorded by Swami Brahmananda in this book that has been translated with the title Words of the Master:
In this video talk Swami Sarvapriyananda says this and and one can hear this from 8 minutes onwards:
Watch "Swami Sarvapriyananda - When You Know Yourself, You Know God - Hollywood - 2021" on YouTube
regards