What is the meaning of violating the Sunnah, and is the act of the Bedouin, "By God, I will not add anything to it nor subtract anything from it," considered a violation of the Sunnah?

Violating the Sunnah means violating the guidance and method of the Prophet, peace and blessings be upon him, and this is indicated by hadiths such as: "Whoever turns away from my Sunnah is not of me." As for one who leaves voluntary acts without turning away from them, and limits himself to the obligatory duties, he will be successful, as is clear from the hadith of the Bedouin who said: "By Allah, I will not add anything to them nor decrease anything."