During the redox reaction in glycolysis which molecule acts as an oxidizing and reducing agent respectively?

When glyceraldehyde-3-phosphate is converted to 1,3 – bisphosphoglycerate the ${\mathrm{NAD}}^{+}$ reduced to $\mathrm{NADH}+{\mathrm{H}}^{+}$. Therefore, ${\mathrm{NAD}}^{+}$ is the oxidizing agent and glyceraldehyde-3-phosphate is the reducing agent.