What is the Chief Ability inducing Awakening?

The Blessed Buddha once said:
Bhikkhus, red sandalwood is known as the best among fragrant and
sweet-scented heartwoods. It is declared to be their chief...
Similarly, among the various states conducive to enlightenment the
Ability of Understanding is declared to be the
best and their chief,
that is, for the swift attainment of this sublime
Enlightenment...!
And what, Bhikkhus, are the states conducive to Enlightenment?
The Ability of
Faith
is a state leading to Awakening!
The Ability of
Energy
is a state leading to Awakening!
The Ability of
Awareness
is a state leading to Awakening!
The Ability of
Concentration
is a state leading to Awakening!
The Ability of
Understanding
is a state leading to Awakening!
Bhikkhus, these
five abilities, developed and cultivated, if
not present,
do not arise except after the arrival of a Perfectly Enlightened One,
a
Tathāgata,
an Arahat! These 5 abilities, which are advanced and refined,
do not
arise except from the Discipline and Teaching of a Well Gone One!

More on the supreme Understanding Ability:
https://What-Buddha-Said.net/drops/Freed_by_Knowing.htm
https://What-Buddha-Said.net/drops/IV/The_Chief_Ability.htm
https://What-Buddha-Said.net/library/DPPN/wtb/n_r/pannaa.htm
https://What-Buddha-Said.net/drops/III/Right_Understanding.htm
https://What-Buddha-Said.net/drops/Understanding_is_the_Chief.htm
https://What-Buddha-Said.net/drops/III/Supreme_Understanding.htm
https://What-Buddha-Said.net/drops/III/Revealing_Understanding.htm
https://What-Buddha-Said.net/drops/III/The_Understanding_Ability.htm
https://What-Buddha-Said.net/drops/III/Outstanding_Understanding.htm
Source (edited extract):
The Grouped Sayings of the Buddha.
Samyutta Nikāya.
Book [V:231-236]
section 48: The Abilities: 55+58+60.
