We do not need to ask anyone whether we have realized emptiness or not; it is very easy to tell just by conducting our own investigation. If our mind is only tranquil, relaxed, and comfortable, this merely implies we are calm and clear- headed. If we do not have a sense of emptiness, we have not attained the Middle Way realization of emptiness. Because in deep sleep we are also very calm, but it is not useful to us; the celestial beings in the form and formless realms, and some non-Buddhists also achieve great equanimity during meditative absorption, but it is hardly useful in eradicating mental afflictions. Hence, the tranquility of the mind is not a measure of realization.
~Depicted from THE FOUR SEALS OF DHARMA - The Practice of Realizing Emptiness