SB 8.19.41

parāg riktam apūrṇaṁ vā
 akṣaraṁ yat tad om iti
yat kiñcid om iti brūyāt
 tena ricyeta vai pumān
bhikṣave sarvam oṁ kurvan
 nālaṁ kāmena cātmane
parāg vā etad riktam akṣaraṁ yad etad om iti tad yat kiñcid om iti āhātraivāsmai tad ricyate; sa yat sarvam oṁ kuryād ricyād ātmānaṁ sa kāmebhyo nālaṁ syāt.
Synonyms: 
parāk — that which separates; riktam — that which makes one free from attachment; apūrṇam — that which is insufficient; — either; akṣaram — this syllable; yat — that; tat — which; om — oṁkāra; iti — thus stated; yat — which; kiñcit — whatever; om — this word om; iti — thus; brūyāt — if you say; tena — by such an utterance; ricyeta — one becomes free; vai — indeed; pumān — a person; bhikṣave — unto a beggar; sarvam — everything; oṁ kurvan — giving charity by uttering the word om; na — not; alam — sufficiently; kāmena — for sense gratification; ca — also; ātmane — for self-realization.
Translation: 
The utterance of the word om signifies separation from one’s monetary assets. In other words, by uttering this word one becomes free from attachment to money because his money is taken away from him. To be without money is not very satisfactory, for in that position one cannot fulfill one’s desires. In other words, by using the word om one becomes poverty-stricken. Especially when one gives charity to a poor man or beggar, one remains unfulfilled in self-realization and in sense gratification.
Purport: 

Mahārāja Bali wanted to give everything to Vāmanadeva, who had appeared as a beggar, but Śukrācārya, being Mahārāja Bali’s familial spiritual master in the line of seminal succession, could not appreciate Mahārāja Bali’s promise. Śukrācārya gave Vedic evidence that one should not give everything to a poor man. Rather, when a poor man comes for charity one should untruthfully say, “Whatever I have I have given you. I have no more.” It is not that one should give everything to him. Actually the word om is meant for oṁ tat sat, the Absolute Truth. Oṁkāra is meant for freedom from all attachment to money because money should be spent for the purpose of the Supreme. The tendency of modern civilization is to give money in charity to the poor. Such charity has no spiritual value because we actually see that although there are so many hospitals and other foundations and institutions for the poor, according to the three modes of material nature a class of poor men is always destined to continue. Even though there are so many charitable institutions, poverty has not been driven from human society. Therefore it is recommended here, bhikṣave sarvam oṁ kurvan nālaṁ kāmena cātmane. One should not give everything to the beggars among the poor.

The best solution is that of the Kṛṣṇa consciousness movement. This movement is always kind to the poor, not only because it feeds them but also because it gives them enlightenment by teaching them how to become Kṛṣṇa conscious. We are therefore opening hundreds and thousands of centers for those who are poor, both in money and in knowledge, to enlighten them in Kṛṣṇa consciousness and reform their character by teaching them how to avoid illicit sex, intoxication, meat-eating and gambling, which are the most sinful activities and which cause people to suffer, life after life. The best way to use money is to open such a center, where all may come live and reform their character. They may live very comfortably, without denial of any of the body’s necessities, but they live under spiritual control, and thus they live happily and save time for advancement in Kṛṣṇa consciousness. If one has money, it should not be squandered away on nothing. It should be used to push forward the Kṛṣṇa consciousness movement so that all of human society will become happy, prosperous and hopeful of being promoted back home, back to Godhead. The Vedic mantra in this regard reads as follows: