SB 1.19.39

nūnaṁ bhagavato brahman
 gṛheṣu gṛha-medhinām
na lakṣyate hy avasthānam
 api go-dohanaṁ kvacit
Word for word: 
nūnam — because; bhagavataḥ — of you, who are powerful; brahman — O brāhmaṇa; gṛheṣu — in the houses; gṛha-medhinām — of the householders; na — not; lakṣyate — are seen; hi — exactly; avasthānam — staying in; api — even; go-dohanam — milking the cow; kvacit — rarely.
Translation: 
O powerful brāhmaṇa, it is said that you hardly stay in the houses of men long enough to milk a cow.
Purport: 

Saints and sages in the renounced order of life go to the houses of the householders at the time they milk the cows, early in the morning, and ask some quantity of milk for subsistence. A pound of milk fresh from the milk bag of a cow is sufficient to feed an adult with all vitamin values, and therefore saints and sages live only on milk. Even the poorest of the householders keep at least ten cows, each delivering twelve to twenty quarts of milk, and therefore no one hesitates to spare a few pounds of milk for the mendicants. It is the duty of householders to maintain the saints and sages, like the children. So a saint like Śukadeva Gosvāmī would hardly stay at the house of a householder for more than five minutes in the morning. In other words, such saints are very rarely seen in the houses of householders, and Mahārāja Parīkṣit therefore prayed to him to instruct him as soon as possible. The householders also should be intelligent enough to get some transcendental information from visiting sages. The householder should not foolishly ask a saint to deliver what is available in the market. That should be the reciprocal relation between the saints and the householders.