While scripture doesn’t directly say, “Masturbation no no, don’t do.” it does say plenty about God’s design for sex and whom it’s designed for. The Bible also says quite a bit about not being self-serving, putting aside one’s own desires and focusing upon others, much less Christ. Masturbation simply put, is a wholly selfish act. Speaking from the male perspective -and one that has fallen more than my fair share down that rabbit hole- doing this puts your mind in the habit of looking at the opposite sex as a pleasure piece, rather than an individual created by God. And if you’re lusting after someone who’s not your spouse? Well… God says a good bit about that too. TL;DR ~ Be like Joseph… flee lust dudes and dudettes.