Shiva Purana
शिलादार्वादिके वापि जले वापि स्थलेपि वा । संशोध्य पीडयेद्वस्त्रं पितृ-णां तृप्तये द्विजाः 1-13-२० ।
The sensible man shall take it to a separate tank or well or to the house itself and beat it on a rock or on a plank to the gratification of the manes, O brahmins.
english translation
zilAdArvAdike vApi jale vApi sthalepi vA । saMzodhya pIDayedvastraM pitR-NAM tRptaye dvijAH 1-13-20 ।
hk transliteration by Sanscript