Mass. Gen. Laws ch. 127 § 88
An inmate of any prison or other place of confinement shall not be denied the free exercise of his religious belief and the liberty of worshipping God according to the dictates of his conscience in the place where he is confined; and he shall not be required to attend any service or religious instruction other than that of his own religious belief, if religious services and instructions of his own belief are regularly held at the institution; and he may, in illness, upon request to the superintendent, keeper, receive the visits of any clergyman whom he may wish. The officers having the management and direction of such institutions shall make necessary regulations to carry out the intent of this section. This section shall not be so construed as to impair the discipline of any such institution so far as may be needful for the good government and safe custody of its inmates, nor prevent the assembling of all the inmates, who do not attend a regularly held religious service of their own belief, in the chapel thereof for such general religious instruction, including the reading of the Bible, as the officer having charge of the institution considers expedient.
Mass. Gen. Laws ch. 127, § 88