matthew 19:12 For there are some eunuchs, which were so born from their mother's womb: and there are some eunuchs, which were made eunuchs of men: and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake. He that is able to receive it, let him receive it. - Free Bible Online

      12. For there are some eunuchs which were so born from their mother's womb--persons constitutionally either incapable of or indisposed to marriage.
      and there are some eunuchs which were made eunuchs of men--persons rendered incapable by others.
      and there be eunuchs which have made themselves eunuchs for the kingdom of heaven's sake--persons who, to do God's work better, deliberately choose this state. Such was Paul (1Co 7:7).
      He that is able to receive it, let him receive it--"He who feels this to be his proper vocation, let him embrace it"; which, of course, is as much as to say--"he only." Thus, all are left free in this matter.

JFB.