As a Muslim (and a theist student of philosophy after all), I recall an interesting Quranic verse which suggests something very similar but with an additional qualifier: "You will never attain goodness until you give out in charity from things you like!" And I'm gonna take this as the starting point of a rather long metaphysical contemplation of the question!
Grand thesis
What does the last qualifier suggest? I think it is there to rule out those acts of charity which are not selfless and self-disinterested. Because ultimately it is the things that we like (or our interests) that determine our true motives. So if you give out in charity for any other purpose than doing good to a fellow human being, for example if you do that for the purpose of wining popularity etc, then that's not an act motivated by true moral incentives (regardless of particular benefits rendered to the recipient). In our religious traditions, this is condemned as "hypocrisy" which however can affect any "good deed."
But this thesis already poses a number of challenges. How can we be convinced and motivated to do something that in no way benefits us personally even if in the sense of a moral satisfaction about our own personality? Other than this realistic "selfish" objection, one could also say if morality is fundamentally about goodness (distinct from acts of goodness as its extension), what justifies depriving one individual (that is ourselves) to benefit another? An intermediate solution could be that in charity the person giving out and the person taking it are not equal in terms of their life satisfaction or wealth. It is the haves that should give out to the have-nots. But this notion already presumes justice and equality as imperative, principles that entail some sort of redistribution of good which involves people relinquishing (either by force of law or consent) obtained interests for the deserving others. Here one can argue that moderation of justice assumes that some interests have been obtained immorally at the cost of others (i.e. the havenots) so justice only restores the rights. But one can't deny that even interests obtained "immorally" still benefit the illegal owner. Hence the dichotomy stands.
And there's a still a more radical form of charity that completely negates self-interest, that is acts of total sacrifice, like one person risking his life to save someone else from fatal danger.
So how do we resolve the realistic conflict between parties' interests that morality as generally understood entails?
I my view only religion can at least reasonably claim to hold the keys to these challenges based on its premises. When you do an act of good you are actually participating in the perfect goodness of God. So in some sense you're just projecting an existing ontological goodness, (essentially distinct from particular instances of worldly interests), on the fellow humans who are less-benefited by the goodness of God! But by doing so, even though you seem to be doing a moral sacrifice which is nonetheless true in appearance, you're in (ontological) reality not! Since participating in Divine goodness, enhances your own personal goodness (with you being an immortal soul) so self-benefit as a realistic basis for morality is also realized.
Hence morality is not in reality the unjustifiable drop of good to be picked by another, with that understood in terms of quantitative discrete distribution of things, but rather multiplying an existing good towards others enabled by the infinite goodness of God endlessly supplying the moral acts! Hence goodness is not distributed discretely so as to result in conflict of interest.
"But all of this sound just pure religious rhetoric!" Could be, but regardless of our personal beliefs about religion, only religion seems to put forward a solution that is at least internally coherent and practically realistic. But to those with ever a religious experience the above wisdom is deeply intuitive and hence immediately verifiable!
Now going to your particular question, I can elaborate further the potency of the above thesis to address difficulties in moral debate.
Answer
I argued that essence of morality is not charity but rather goodness with goodness being an ontological reality embracing us all (but let's just forget about the problem of evil for now if it is occurring your mind. We just want to show how well the thesis works regardless of other theological problems). And charity is an act of extending, multiplying goodness to/for others.
When the above is established, on can then hardly determine when charity is "enough". Participating in infinite goodness allows for extending goodness indefinitely (although not infinitely since we are all mortal and practically restricted in doing so by our internal and external circumstances).
But what then dictates how much charity we give out? The extend to which we have personally realized goodness! That is only so far as we have actualized goodness in ourselves we can extend it to others! This explains why there are those human angels and saints who can surprise us with their "unending" generosity and why there are villans who can't do but bad!
Are we then hypocrites? We are hypocrites to the extend that claim to be good without having an internally realized goodness necessary for supporting the envisioned act of goodness! That is without a realized goodness, engaging in charity is an impossibility. If it seems otherwise then we can be sure that there are profane selfish motives disguised under generous pretensions with the remarkable consequence that goodness is not actually multiplied, hence the hypocrite having to extract goodness from somewhere else to compensate the relinquished good! This is a feature of all "profane" hypocritical acts of goodness! (Profane is meant to mark the ontological dynamics behind what religions actually suggest with the concept. It is never meant as to dismiss acts of good by the non-religious).
As for the question of duties to close ones. An important note first: Duties are only conventions aimed at enforcing a minimum degree of participation in the infinite good as deemed by the law-giver (state or religious law) for individuals! Hence saints don't define their "duties" by the conventions for general humanity. They pour out goodness so large as their deep participation in the absolute goodness enables them! But they also do it wisely, not to waste it! What this means would take another post of this length so let's move on!
Now should we value those closer to us? Practically there are "good" arguments for this ruling as well as ontologically (since no practically feasible convention is without underlying ontological reasons)! Families and relatives are areas of our worldly existence where perfect goodness has already manifested itself most prominently hence they are areas that are essentially more conductive for further participation and projection of the perfect goodness! Hence religions encourage you to start charity, care and benevolence from your close ones, the neighbors and then the strangers! Families are the loci from where the good garden of humanity should blossom and populate! Peace!
