"And what is right concentration? There is the case where a monk -- quite withdrawn from sensuality, withdrawn from unskillful (mental) qualities -- enters & remains in the first jhana: rapture & pleasure born from withdrawal, accompanied by directed thought & evaluation. With the stilling of directed thought & evaluation, he enters & remains in the second jhana: rapture & pleasure born of composure, unification of awareness free from directed thought & evaluation -- internal assurance. With the fading of rapture he remains in equanimity, mindful, & fully alert, and physically sensitive of pleasure. He enters & remains in the third jhana, and of him the Noble Ones declare, 'Equanimous & mindful, he has a pleasurable abiding.' With the abandoning of pleasure & pain -- as with the earlier disappearance of elation & distress -- he enters & remains in the fourth jhana: purity of equanimity & mindfulness, neither pleasure nor pain. This is called right concentration."-- SN XLV.8
"I tell you, the ending of the mental fermentations depends on the first jhana...the second jhana...the third...the fourth...the sphere of the infinitude of space...the sphere of the infinitude of consciousness...the sphere of nothingness. I tell you, the ending of the mental fermentations depends on the sphere of neither perception nor non-perception."-- AN IX.36
"These are the four developments of concentration. Which four? There is the development of concentration that, when developed & pursued, leads to a pleasant abiding in the here & now. There is the development of concentration that, when developed & pursued, leads to the attainment of knowledge & vision. There is the development of concentration that, when developed & pursued, leads to mindfulness & alertness. There is the development of concentration that, when developed & pursued, leads to the ending of the effluents.(1) "And what is the development of concentration that, when developed & pursued, leads to a pleasant abiding in the here & now? There is the case where a monk -- quite withdrawn from sensuality, withdrawn from unskillful qualities -- enters & remains in the first jhana: rapture & pleasure born from withdrawal, accompanied by directed thought & evaluation. With the stilling of directed thought & evaluation, he enters & remains in the second jhana: rapture & pleasure born of composure, unification of awareness free from directed thought & evaluation -- internal assurance. With the fading of rapture he remains in equanimity, mindful & alert, and physically sensitive of pleasure. He enters & remains in the third jhana, and of him the Noble Ones declare, 'Equanimous & mindful, he has a pleasurable abiding.' With the abandoning of pleasure & pain -- as with the earlier disappearance of elation & distress -- he enters & remains in the fourth jhana: purity of equanimity & mindfulness, neither pleasure nor pain. This is the development of concentration that...leads to a pleasant abiding in the here & now.
(2) "And what is the development of concentration that... leads to the attainment of knowledge & vision? There is the case where a monk attends to the perception of light and is resolved on the perception of daytime [at any hour of the day]. Day [for him] is the same as night, night is the same as day. By means of an awareness open & unhampered, he develops a brightened mind. This is the development of concentration that, when developed & pursued, leads to the attainment of knowledge & vision.
(3) "And what is the development of concentration that... leads to mindfulness & alertness? There is the case where feelings are known to the monk as they arise, known as they persist, known as they subside. Perceptions are known to him as they arise, known as they persist, known as they subside. Thoughts are known to him as they arise, known as they persist, known as they subside. This is the development of concentration that, when developed & pursued, leads to mindfulness & alertness.
(4) "And what is the development of concentration that...leads to the ending of the effluents? There is the case where a monk remains focused on arising & falling away with reference to the five aggregates for sustenance/clinging: 'Such is form, such its origination, such its passing away. Such is feeling... Such is perception... Such are fabrications... Such is consciousness, such its origination, such its disappearance.' This is the development of concentration that, when developed & pursued, leads to the ending of the effluents.
"These are the four developments of concentration."
-- AN IV 41
"Now what, monks, is noble right concentration with its supports & requisite conditions? Any singleness of mind equipped with these seven factors -- right view, right resolve, right speech, right action, right livelihood, right effort, & right mindfulness -- is called noble right concentration with its supports & requisite conditions."-- MN 117
"Rouse yourself! Sit up! What good is there in sleeping? For those afflicted by disease (suffering), struck by the arrow (craving), what sleep is there?"Rouse yourself! Sit up! Resolutely train yourself to attain peace. Do not let the king of death, seeing you are careless, lead you astray and dominate you."
-- Sn II.10
"Over there are the roots of trees; over there, empty dwellings. Practice jhana, monks. Don't be heedless. Don't later fall into regret. This is our message to you."-- SN XXXV.145