\documentclass[fleqn]{article}
\usepackage{amsmath}
\show\equation
\usepackage{hyperref}
\show\equation
\begin{document}
\show\equation
\section{a}
\section{b}
\tracingmacros=1
\begin{equation}
a + b = c
\label{eq:a}
\end{equation}
\tracingmacros=0
\ref{eq:a}
\end{document}