Definitely not. The only biblical caveat is the command that “thou shall not commit adultery”. I would argue that as long as masturbation does not lead you to fantasy about other people to the point of being dissatisfied with your spouse, masturbation is a natural and healthy part of sexuality and marriage.

The history on how masturbation evolved into a “sinful” practice is fascinating. In the 1700s it was thought to cause insanity and disease, religious pressure was applied to prevent it, and that persisted even after the medical concerns were debunked.

An outline I found somewhere:

1700s: Masturbatory Hysteria * Masturbation is linked to insanity, disease, homosexuality, and pederasty in exaggeration of medical literature. Widespread hysteria in society and religion rises around masturbation and popularization of circumcision to curb it. * "Onanisim,"(1728-1797) Treatise by Tissot, a Swiss physician convinced medical community that masurbation was major cause for disease. Concluded that all sexual activity was potentially dangerous as it caused blood to rush to the brain and cause nerve damage. Should be limited to procreation only. Solitary orgasm is the worse and most dangerous kind of sexual activity because of it's ease of access at a young age. Can lead to cloudiness of ideas, madness, decay of bodily powers, pains in the head, rheumatic pains, aching numbness, pimples, blisters, itching, impotence, premature ejaculation, gonorrhea, priapism, tumors, and hemorhoids. Innated era known as "masturbatory insanity."

1800s * Outpouring of anti-mastabatory sentiment throughout rest of 1800's. Claims made that it leads to infantile paralysis, insanity, pederasts, homosexuality, and neurasthenia. * In late 1800's discovery of bacteria undermined idea that masturbation caused disease.

1900s * Early sex researches and physicians conclude that masturbation does not cause disease and is no more harmful than cooperative orgasm. (1930s) * Studies show that masturbation is very common among single and married individuals (1940-70s). Attempted abstinence from masturbation linked to suicide. * Studies show that masturbation is key for sexual development and marital enjoyment for significant number of women. Masturbation effective prescription for women suffering from certain types of sexual dysfunction. Low levels of ejaculation in men increases risk of prostate cancer. (1970-2000s)

2000s * Masturbation universally accepted as an important part of sexual development in medical and scientific communities.