Can you please explain this equality?

$$\int \frac{r}{{\sigma}^{2}}\mathrm{exp}\left(\frac{-{r}^{2}}{2{\sigma}^{2}}\right)\phantom{\rule{thickmathspace}{0ex}}dr=-\mathrm{exp}\left(\frac{-{r}^{2}}{2{\sigma}^{2}}\right)$$

$$\int \frac{r}{{\sigma}^{2}}\mathrm{exp}\left(\frac{-{r}^{2}}{2{\sigma}^{2}}\right)\phantom{\rule{thickmathspace}{0ex}}dr=-\mathrm{exp}\left(\frac{-{r}^{2}}{2{\sigma}^{2}}\right)$$