I found the solution. I'm sharing it in case it helps someone.
private static final ResourceLocation image = new ResourceLocation(Main.MODID, "textures/gui/image.png");
@SubscribeEvent
public static void onRenderGui(RenderGuiOverlayEvent event) {
RenderSystem.disableDepthTest();
RenderSystem.depthMask(false);
RenderSystem.enableBlend();
RenderSystem.setShader(GameRenderer::getPositionTexShader);
RenderSystem.blendFuncSeparate(GlStateManager.SourceFactor.SRC_ALPHA, GlStateManager.DestFactor.ONE_MINUS_SRC_ALPHA, GlStateManager.SourceFactor.ONE, GlStateManager.DestFactor.ZERO);
RenderSystem.setShaderColor(1, 1, 1, 1);
event.getGuiGraphics().blit(image, 0, 0, 0, 0, 64, 64, 64, 64);
RenderSystem.depthMask(true);
RenderSystem.defaultBlendFunc();
RenderSystem.enableDepthTest();
RenderSystem.disableBlend();
RenderSystem.setShaderColor(1, 1, 1, 1);
}