I'm certainly not qualified to talk about Mahamudra, but I found the Third Karmapa's text, "Aspiration Prayer for Mahamudra," to be very beautiful and inspiring.
My favorite lines are:
Beings by nature have always been Buddhas,
Yet not realizing this, they wander endlessly in samsara.
May we have unbearable compassion
For sentient beings whose suffering knows no bounds.
This unbearable compassion radiates unceasing love,
And as it does, its emptiness of essence nakedly shines.
May we never leave this supreme and unerring path of union,
May we meditate upon it all day and all night.