Here the Buddha preaches that being mindful of the Buddha's white tuft between eyebrows even for an instant can eradicate innumerable evil karma.
Here,After my passing away, there will be some disciples of the Buddha, who abandon all evil, leave disturbances, enjoy practicing little speech, and are not engaged in much business. Among the six periods of the day even for a moment out of the small fraction of each period they will be able to put their minds on the white tuft[between the brows] of the Buddha and make their minds clear and stable without erroneous images. If they unceasingly put their mind on the Buddha’s white tuft, whether they can see the mark or not, they will remove the sins[accumulated through the] transmigration for as many kalpas as the number of motes of dust[amounting to] the number of grains of sand of the nine billion six hundred nayutas of the Ganges river.
Furthermore, (if one) only hears about the white tuft and being pleased, faithfully accepts it without surprise or doubt, that person will also remove the sins[accumulated through the] transmigration for eight billion kalpas.
(The sutra on the Ocean-like Samadhi of the Visualization of the Buddha)
I will explain the definition of nayuta according to the Mahavaipulya sutra of Buddha Adornment - The Ineffable, Time Spans, Bodhisattva Abodes.
Here 100 laksa is 10 millionThe Buddha said, “Good man, a hundred lakṣa is a koṭi. A koṭi times a koṭi is an ayuta. An ayuta times an ayuta is a nayuta.
So even a nayuta would be 10^28.
The number nine billion six hundred nayutas would be beyond our grasp.
But Buddha's says evil karmas of kalpas equal to as many sand grains of nine billion six hundred nayutas Ganges river, the number which only the Buddha can understand.
This shows the remarkable power of the mindfulness of even one mark of the Buddha for even an instant.
So what would be the great benefit if we all are mindful of the Buddha sincerely for our lives.
Inserting Buddha image to help in visualization
Namo Sakyamuni Buddha
Namo Amitabha Buddha