📖Guruda Purana Agastya Samhita, Chapter 50: The most excellent form of bathing, namely, Vayavya, consists in rubbing on the body the powder of cow-dung
📖Srimad Bhagavatam 10.6.20
The child was thoroughly washed with cow urine and then smeared with the dust raised by the movements of the cows. Then different names of the Lord were applied with cow dung on twelve different parts of His body, beginning with the forehead, as done in applying tilaka. In this way, the child was given protection.
One should always bathe, using cow-dung. One should sit on dried cowdung. One should eat, sitting on a cowhide purified by dipping it in water.
Releted: Drink cow urine in Hinduism