Those creatures, which by their original make are so constituted, that their desires and their duty always necessarily coincide, can't, I think, be said to have any claim to a reward: whereas those who are surrounded with difficulty and temptation, and who are obliged to deny themselves and submit to great inconveniences that they may maintain their integrity, if notwithstanding this, they do behave uprightly, seem on this account to have an equitable claim to it.

-- Thomas Bayes

(The first type of entity sounds like a properly designed FAI - there is certainly no need to feed it any rewards, it does what it does because that's what it wants to do. The second type of entity sounds like some sort of UFAI with tacked on 'safety' measures. It might make sense to reward it with some paperclips every day it manages not to destroy humanity. Pretty sure this was not where Bayes was going with this, though.)