Bg 17.20

datavyam iti yad danam
diyate ’nupakarine
dese kale ca patre ca
tad danam sattvikam smrtam

Word for word: 
datavyam — worth giving; iti — thus; yat — that which; danam — charity; diyate — is given; anupakarine — irrespective of return; dese — in a proper place; kale — at a proper time; ca — also; patre — to a suitable person; ca — and; tat — that; danam — charity; sattvikam — in the mode of goodness; smrtam — is considered.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Charity given out of duty, without expectation of return, at the proper time and place, and to a worthy person is considered to be in the mode of goodness.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In the Vedic literature, charity given to a person engaged in spiritual activities is recommended. There is no recommendation for giving charity indiscriminately. Spiritual perfection is always a consideration. Therefore charity is recommended to be given at a place of pilgrimage and at lunar or solar eclipses or at the end of the month or to a qualified brahmana or a Vaisnava (devotee) or in temples. Such charities should be given without any consideration of return. Charity to the poor is sometimes given out of compassion, but if a poor man is not worth giving charity to, then there is no spiritual advancement. In other words, indiscriminate charity is not recommended in the Vedic literature.