He [Śukadeva Gosvāmī] was accustomed to stay at the door of a householder only long enough for a cow to be milked. And he did this just to sanctify the residence.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स गोदोहनमात्रं हि गृहेषु गृहमेधिनाम् । अवेक्षते महाभागस्तीर्थीकुर्वंस्तदाश्रमम्
sa godohanamātraṃ hi gṛheṣu gṛhamedhinām | avekṣate mahābhāgastīrthīkurvaṃstadāśramam
SB 1.4.8