Skandapurana 4.36.48

4.36.48

sāvitrīpatitaiḥ sārdhaṃ saṃbaṃdhaṃ na samācaret ..

One should not enter into relations with those who have fallen from the Sāvitrī. / For the twice-born, the skin [should be] of a black antelope, a ruru deer, and a goat, respectively. (24)