Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 34

Sanskrit:

दानस्य तपसो वापि यच्चेष्टापूर्तयो: फलम् ।प्रवासस्थस्य यो धर्मो यश्च पुंस उतापदि ॥ ३४ ॥

ITRANS:

dānasya tapaso vāpiyac ceṣṭā-pūrtayoḥ phalampravāsa-sthasya yo dharmoyaś ca puṁsa utāpadi

Translation:

Please also describe the fruitive results of charity and penance and of digging reservoirs of water. Please describe the situation of persons who are away from home and also the duty of a man in an awkward position.

Purport:

The digging of reservoirs of water for public use is a great work of charity, and retiring from family life after fifty years of age is a great act of penance performed by the sober human being.