Srimad Devi Bhagawatam

"If anybody, out of his amorous passion casts his semen privately [masturbation] on the surface of the ground, he will have to suffer the torments of hell for as many years as are the numbers of dust particles on that area." - The S'rîmad Devî Bhâgawatam, Ninth Book, Chapter Ten

"If any woman or any man makes another of a different sex eat semen, out of passion, he goes to S’ukra Kunda where he drinks semen for one hundred years. Then he crawls about as worms for one hundred years. And then he gets purified." - The S'rîmad Devî Bhâgawatam, Ninth Book, Chapter Thirteen