Quotes from The Buddha Treasury Sutra
“Śāriputra, this dharma of bearing the Buddha in mind cuts off the path of language; it is beyond all thoughts and in the practice of this dharma no thought can be apprehended, such is called bearing the Buddha in mind.
“Śāriputra, all thoughts are characterized by quiescence and cessation; to be in accord with such a dharma is called the cultivation of bearing the Buddha in mind. One should not bear the Buddha in mind relying on any form. Why is that? Thinking of forms leads to the apprehension of appearance; desiring specific qualities breeds discernment. The notion of bearing the Buddha in mind is that which is without shape, appearance, conditions, or properties. Hence one should know: the true way of bearing the Buddha in mind is without differentiation, apprehension, and abandonment.
“Bearing the Buddha in mind denotes the shattering of investigation and analysis toward everything good or ill; it is without investigation or analysis, and is thoughtless and quiescent. Why is that? One should not employ thought and examination to be mindful of Buddha. The absence of investigation and analysis is called the pure way of bearing the Buddha in mind.
“You should not attach to even the slightest thoughts when you bear the Buddha in mind, nor should you develop conceptual proliferation or differentiation. Why is that? All dharmas are empty of an inherent nature; hence, you should not be mindful of any kind of sign. The notion of signlessness is the true way of being mindful of Buddha.”