"Have you considered if he is upon guidance, or enjoins righteousness?" He is Muhammad; he was upon guidance and he enjoined the servants to obey Allah.
﴿أَرَأَيْتَ إِنْ كَانَ عَلَى الْهُدَى أَو أَمر بالتقوى﴾ وَهُوَ مُحَمَّدٌ، كَانَ عَلَى الْهُدَى وَأمر الْعباد بِطَاعَة الله.