Friends:

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 & their chief,
that is, for the rapt 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 unarisen,
do not arise except after the arrival of a Perfectly Enlightened One,
a Tathagata, an Arahat! These five abilities, advanced and refined,
do not arise apart from the Discipline & Teaching of Well Gone One!

More on the supreme Understanding Ability:
http://What-Buddha-Said.net/drops/Freed_by_Knowing.htm
http://What-Buddha-Said.net/drops/IV/The_Chief_Ability.htm
http://What-Buddha-Said.net/library/DPPN/wtb/n_r/pannaa.htm
http://What-Buddha-Said.net/drops/III/Right_Understanding.htm
http://What-Buddha-Said.net/drops/Understanding_is_the_Chief.htm
http://What-Buddha-Said.net/drops/III/Supreme_Understanding.htm
http://What-Buddha-Said.net/drops/III/Revealing_Understanding.htm
http://What-Buddha-Said.net/drops/III/The_Understanding_Ability.htm
http://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.

The Ability to Understand is the Highest!