Yosef Karo, Translation:Shulchan Aruch — Even ha-Ezer 23Prohibitions against spilling one’s seed needlessly and…
“ A man is not to look at domestic animals, wild beasts or fowl when they are mating. However, an animal breeder is permitted to insert the male organ into the female because he is focused on his work and will not have [sexual] thoughts. Paragraph 4- An unmarried man is forbidden from putting his hand on his genitals, lest this lead him to [sexual] thoughts. He should not extend his hand below his navel, lest he be led to [sexual] thoughts. When urinating, he must not hold the shaft of his penis, but if he is married then this is allowed. ”
