$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
3.66
\begin{equation} \begin{gathered}\label{equation:n-connective-for-simplicial-set} \xymatrix@R =50pt@C=50pt{ X \ar [r] \ar [d]^{f} & X' \ar [d]^{f'} \\ Y \ar [r] & Y', } \end{gathered} \end{equation}