I am wondering about an apparent conflict between a call for selfless love topped with a promise of a reward for it. Simply speaking, one is called to behave well (love ones neighbour) out of kindness (certainly not selfishness), but at the same time a reward is promised (those who behave well eventually go to heaven). This seems to entangle selflessless with selfishness in an uncomfortable way.
The following example hopefully illustrates my concern. Suppose I am encouraging my kid to go help a person in need by appealing to the kid's kindness and compassion. But when done with encouraging, I add "by the way, you will get $10 if you help him/her". This seems to defeat the point of the motivation through kindness and selflessness.
In yet other words, I am concerned that on the one hand there is a morality, an ideal that is attractive for a well-wishing person, but the promise of a reward downgrades this to an act of buying and selling (I do this and then you give me that).
Worse yet, the promise of a reward removes the opportunity to choose selflessness over selfishness. There is no longer a choice between behaving selflessly and behaving selfishly because both lead to the same actions in life.