One who lives considering these
cautiously, resolutely and enthusiastically,
may either enter the state of
Nibbāna right here and now in this very life,
or if there is remaining traces of clinging, the state of
non-return...
Those who neglect understanding
Suffering,
The Cause of Suffering,
The End of Suffering,
and
The Way all Suffering is completely eliminated,
are incapable of release by understanding, are incapable of mental release,
are incapable of direct knowledge, and are thereby incapable of making an end...
While those who undertake
to develop real understanding of
This Suffering,
The Cause of Suffering,
The End of Suffering,
and
The Way to End Suffering,
are indeed capable of mental release
by understanding, direct knowledge,
and thus also capable of making an end...

Dig further here on the 4 Great and Noble Truths:
https://What-Buddha-Said.net/drops/II/The_1st_Noble_Truth_on_Suffering.htm
https://What-Buddha-Said.net/drops/II/The_2nd_Noble_Truth_on_The_Cause_of_Suffering.htm
https://What-Buddha-Said.net/drops/II/The_3rd_Noble_Truth_on_The_Ceasing_of_Suffering.htm
https://What-Buddha-Said.net/drops/II/The_4th_Noble_Truth_on_The_Way_to_Cease_Suffering.htm

Source: The Bundle of Threads. The
Sutta-Nipāta 724-765
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/kn/snp/index.html