Semen is the strength of the body, its life [force], and the light of the eyes; the greater the emission [of sperm], [the greater] the damage to the body, to its strength and the greater the loss to one's life [span]. This was implied by Solomon in his wisdom: "Do not give your strength to women" (Proverbs 31:3).
Whoever is steeped in sexual relations, old age springs upon him [before its time], his strength is depleted, his eyes become dim, a foul odor emanates from his mouth and his armpits, the hair of his head, his eyebrows, and eyelashes fall out, the hair of his beard, armpits, and legs grows in abundance, his teeth fall out and he suffers many pains beyond these. The wise of the doctors have said: One of a thousand dies from other illnesses and a thousand from excessive intercourse.
Therefore, a person must take care in this matter if he wishes to live in good [health]. He should not engage in intercourse except when the body is healthy and particularly strong, when he has many involuntary erections, the erection is still present even when he makes an effort to think of something else, he finds a heaviness from the loins and below, the tendons of the testicles seem to be stretched, and his flesh is warm. Such a person needs to engage in intercourse and it is medically advisable.
He should not engage in intercourse on a full or empty stomach, but after the food has been digested. He should examine himself to see if he needs to move his bowels before and after intercourse. He should not engage in intercourse while standing or sitting, nor in the bathhouse, nor on a day on which he goes to the bathhouse, nor on a day on which he lets blood, nor on the day he departs on a journey or arrives from a journey, nor [on the day] before or afterwards.