Unbinding
Nibbāna Sutta  (AN 4:179)

Then Ven. Ānanda went to Ven. Sāriputta and, on arrival, exchanged courteous greetings with him. After an exchange of friendly greetings & courtesies, he sat to one side. As he was sitting there, he said to Ven. Sāriputta, “Friend Sāriputta, what is the cause, what is the reason, why some beings do not become totally unbound in the present life?”

“There’s the case, friend Ānanda, where beings do not discern, as it has come to be, that ‘This perception has a share in decline;’ ‘This perception has a share in stability;’ ‘This perception has a share in distinction;’ ‘This perception has a share in penetration.’1 This is the cause, this is the reason, why some beings do not become totally unbound in the present life.”

“And what, friend Sāriputta, is the cause, what is the reason, why some beings do become totally unbound in the present life?”

“There’s the case, friend Ānanda, where beings discern, as it has come to be, that ‘This perception has a share in decline;’ ‘This perception has a share in stability;’ ‘This perception has a share in distinction;’ ‘This perception has a share in penetration.’ This is the cause, this is the reason, why some beings become totally unbound in the present life.”

Note

1. A perception with a share in decline is one that causes the mind to fall from concentration. A perception with a share in stability is one that helps to maintain concentration. A perception with a share in distinction is one that leads to higher stages of concentration. A perception with a share in penetration is one leading to liberating insight.

See also: MN 118; AN 4:49; AN 7:46; AN 10:60