What would be the motivation for an arahant to perform generous deeds?
"Compassion is characterized as promoting the aspect of allaying suffering. Its function resides in not [enduring] others' suffering. It is manifested as non-cruelty. Its proximate cause is to see helplessness in those overwhelmed by suffering. It succeeds when it makes cruelty subside, and it fails when it produces sorrow." -Visuddhimagga

Compassion is a wholesome quality of the mind. It's not eliminated when one attains enlightenment. So when an Arahath's mind focuses on the suffering of a being, compassion arises naturally.

Craving is what is eleminated when one attains enlightenment. Craving is of 3 kinds.


Desire for sensual pleasure
Desire for becoming
Desire for non-becoming