Śatapatha Brāhmaṇa ("of a hundred paths") 13.8.1.9

13.8.1.9

yasyaiva samasya sataḥ dakṣiṇatah purastādāpa etya saṃsthāyāpraghnatya etāṃ diśamabhiniṣpadyākṣayyā apo'pipadyeraṃstatkuryādannam vā'āpo'nnādyamevāsmā'etatpurastātpratyagdadhātyamṛtamu vā āpa eṣo ha jīvānām digantareṇa saptarṣīṇāṃ codayanamādityasyacāstamayanamamṛtameva tajjīveṣu dadhāti taddhaitatpratimīvannāma śmaśānakaraṇam jīvebhyo hitaṃ yadvāva jīvebhyo hitam tatpitṛbhyaḥ

On any level (ground) where the waters, flowing thither from a south-easterly direction, and coming to a stand-still, will, on reaching that (north-westerly) quarter, without pressing forward, join imperishable water, on that (ground) one may make (the tomb); for, water being food, one thereby offers food to him from the front towards the back; and, water being the drink of immortality, and that region between the rising of the seven Rishis and the setting of the sun being the quarter of the living, one thereby bestows the drink of immortality upon the living:--and such a one, indeed, is a closing tomb; and verily what is good for the living that is also good for the Fathers.