The Buddha Treassury Sutra, Vol. 1
“Śāriputra, what is meant by bearing the Buddha in mind? Seeing that which is without anything is called bearing the Buddha in mind. Śāriputra, Buddhas are unquantifiable [for Buddhas are intangible], inconceivable, and immeasurable. Thus, the seeing of that which is without anything is called bearing the Buddha in mind. It essentially denotes non-differentiation. As all Buddhas connote non-differentiation, it is said that the non-differentiated mind bears the Buddha in mind."
"Furthermore, seeing the Ultimate Reality of all dharmas is called seeing the Buddha. What denotes the Ultimate Reality of all dharmas? All dharmas refer to the ultimately empty and without anything, and bearing the Buddha in mind means seeing all dharmas as ultimately empty and without anything. Moreover, in this dharma (the Ultimately Reality), not even the subtlest thought is apprehensible; such is called bearing the Buddha in mind.”
Excerpts from Signless Buddha Mindfulness
Venerable Xiao Pingshi
The above excerpts from the Buddha Treasury Sūtra describe the state of Buddha-mindfulness in Ultimate Reality (C: 實相念佛). Having realized the True Mind, a practitioner will know that the “Buddha” is without physical form and appearance or any phenomenal characteristic. When this person follows others in chanting the Buddha’s name, he can say that “the recitation of the Buddha’s name encompasses both phenomenon and principle.” However, for those who have not yet realized the True Mind, making the same comment frequently and casually constitutes false speech. What accounts for the difference? In the latter case, one has realized neither the phenomena nor the principle of Buddha-mindfulness.
Signless Buddha Mindfulness, p. 15
The mastery of the practice of Signless Buddha-mindfulness imparts a sense of self-assurance in a practitioner. He will be confident that he is on the right track of dharma cultivation. He will no longer be plagued by doubts and misgivings and can thus naturally forge ahead with his practice.
Signless Buddha Mindfulness, p.125