SB 8.16.26
sinivalyam mrdalipya
snayat kroda-vidirnaya
yadi labhyeta vai srotasy
etam mantram udirayet
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
If dirt dug up by a boar is available, on the day of the dark moon one should smear this dirt on his body and then bathe in a flowing river. While bathing, one should chant the following mantra.