What Intentional
Actions (Kamma) influence Life-Length?

A student once asked the Buddha:
Master Gotama, what is the cause and condition why some human beings
here are short-lived, while other human beings are long-lived?
The Blessed Buddha then explained:
Here, friend, some man or woman kills living beings and is murderous,
bloody-handed, enjoying rage and violence, cruel to all living beings!
Because of intending and undertaking such action, at the breakup of
the body, right after death, such one reappears in a state of affliction,
in a painful destination, in the purgatory, or even in the hells...
But if such one at the
breakup of the body, after death, is not reborn
in an awful state, a painful destination, the purgatory, or in the hells,
but instead comes back to the human state, then wherever such one is
reborn
he is short-lived#! These are the actions, friend, that leads to a
short future life,
namely, kill, murder, bloody-handed brutality, slaughter,
violence, and cruelty towards all living beings...
However, friend, any man or woman, who is avoiding
all killing of
any living
beings, who abstains from killing any living being, with
both rod and weapon
laid down, gentle and kind, such one
dwells harmless to all living beings...
Because of intending
and undertaking such behaviour, at breakup of the body,
right after
death, such one reappears in a pleasurable and happy destination,
even in the divine dimensions! But if at the breakup of the body, right after
death, such one is not reborn in a happy destination, in the heavenly worlds,
but instead comes back to a human state, then wherever such one reappears,
such one is long-lived%! This
is the way, friend, leading to long life, namely,
avoiding the killing of any living being, refraining from killing living beings,
with stick and weapon
laid aside, gentle and kind, one abides compassionate
to all sentient beings,
completely harmless to all
living and breathing beings...!

Notes:
#: Such one escapes hell, because the evil kamma is modified by
past good!
%: Such one misses heaven, because the good kamma is modified by past evil!
For details on the mechanics
of Kamma = Intentional Action see:
https://What-Buddha-Said.net/drops/II/Kamma_is_intention.htm
https://What-Buddha-Said.net/drops/II/Buddha_on_Kamma.htm
https://What-Buddha-Said.net/drops/II/Good_Action_dilutes_Evil_Kamma.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_short_vs_long_life.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Health_vs_Sickness.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Low_or_High_Birth.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Wealth_or_Poverty.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Beauty_vs_Ugliness.htm
https://What-Buddha-Said.net/drops/II/Effect_of_kammic_Action_is_Delayed.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Power_or_Disrespect.htm
https://What-Buddha-Said.net/drops/II/Evil_Kamma_enhances_other_Evil_Kamma.htm
https://What-Buddha-Said.net/drops/II/Good_Action_enhances_other_Good_Kamma.htm
https://What-Buddha-Said.net/drops/II/Kamma_leading_to_Stupidity_or_Intelligence.htm

Source:
The Moderate speeches of the
Buddha: The short speech on Action. MN 135
http://store.pariyatti.org/Middle-Length-Discourses-of-the-Buddha_p_1543.html
Full Text:
http://www.accesstoinsight.org/tipitaka/mn/mn.135.nymo.html