Manava Dharmashastra 4.47

4.47

na gacchannāpi ca sthitaḥ | gacchatastiṣṭhataśca pratiṣedhādāsīnasyābhyanujñānam | na cāsanne nadītīre, nadījale na | saṃsargaśaṅkā yatra bhavati tadāsannam | parvatasya mastakaṃ śṛṅgam |

Medhātithi’s commentary (manubhāṣya):
‘Nor walking, nor standing.’—By the prohibition of passing urine while walking or standing, it is implied that one should pass urine sitting. Nor very close to the river, nor in the river itself; that is to be regarded as ‘very close’ where there is fear of the urine touching the river.

“Mountain-top”—Peak.—(47)