The concluding words of this hadith are an admonition. Turning away from the Sunnah of Allah’s beloved Messenger puts one’s Islam in doubt. It is not possible to exceed him (sal Allahu alaihi wa sallam) in piety. Whatever one tries to do against the teachings of the Prophet (sal Allahu alaihi wa sallam) is a distortion of the religion.
In this hadith we are warned against adopting the extremism of the people of earlier religions, who forbade for themselves those things which Allah (subhana wa ta’ala) had made lawful for them. Then they were not able to live up to these self imposed hardships.
Islam is the religion of the Fitrah; it corresponds to human nature. Allah (subhana wa ta’ala) has only forbidden us those things which harm our Dunya or Akhirah. It is extremely unwise to start adding or subtracting from this list. Doing so implies knowing better than Allah; while no-one knows better than Him and no-one loves us more than Him.