# How to give some text an equation number

I want to be able to write the following in LaTeX

    We make the further assumption that
$$\label{eqn:assumption} There is a bounded linear operator B:X\to X^* such that B^*=B and the operator JB is an extension of T'(0)$$


and get a nice output, in such a way that this whole chunk of text along with the math can be referenced later. Of course I can write text inside the equation environment using \text{}, but when I tried this the spacing was all wrong. Can anyone suggest a solution to this?

Use a minipage

\documentclass{article}
\usepackage{amsmath}
\begin{document}
We make the further assumption that
$$\label{eqn:assumption} \begin{minipage}{0.9\textwidth} There is a bounded linear operator B:X\to X^* such that B^*=B and the operator JB is an extension of T'(0) \end{minipage}$$
\end{document}


For example (the value is only exemplary):

\documentclass{article}
\usepackage{amsmath}

\begin{document}

We make the further assumption that
$$\label{eqn:assumption} \text{\begin{tabular}{p{0.85\linewidth}} There is a bounded linear operator B\colon X\to X^* such that B^*=B and the operator JB is an extension of T'(0) \end{tabular} }$$

\end{document}