Upacala Defeats Mara
This poem is from the Therigatha. The Therigatha preserves 73 poems of elder nuns and is the ninth section in the Khuddaka Nikāya. The Khuddaka Nikāya is a collection of short texts in (mostly) verse. The Khuddaka Nikāya is the last Nikaya (collection) of the Sutta Piṭaka, the second book of the Pāli Canon.
Here, Upacala teaches how she has overcome suffering by establishing refined mindfulness and gaining insight into impermanence, not-self, and suffering through developing to its culmination the Eightfold Path. [1,2]
Mara is metaphor for a mind rooted in ignorance and prone to confusion, deluded thinking, and ongoing unsatisfactory experiences. 
The links below to further study show the depth of understanding presented here.
Upacālā Defeats Mara
Established in mindfulness, having developed Right View,
I have entered the peaceful state,
of which those ignorant (of FourTruths) 
Ignore those truths,
and enjoy sensual pleasures,
delight in sensual pleasures.
Don’t later burn with regret.
One who gives birth to ignorance,
clinging to impermanence,
clinging to ignorant views, (of self)
suffers, and suffers more.
The Rightly Self-Awakened one,
has defeated Mara.
He taught me his Dhamma,
for the cessation of ignorance,
the cessation of fabrications. 
He taught me the Eightfold Path,
for final cessation of suffering.
I heard the great teachers words,
I am delighted in his bidding.
Insight into the Three Marks is known,
I have done what must be done.
Craving has ended,
Know this, evil one, (Mara)
you have been defeated!
End of Poem