I agree that what we do in the spiritual field is not to expect any reward from the creator (God), even we should not expect heaven, but we expect only the pleasure of the creator for what we do. We do not know by what deeds or practices we get heaven. May be with a small act we can get heaven because we do sincerely. But we do not get any reward from the creator because we do not do sincerely even though the act is great by spending a lot of time and money.