It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The Sunnah is of two kinds: a sunnah that relates to an obligation and one that does not relate to an obligation. The sunnah that relates to an obligation has its basis in the Book of Allah; adopting it is guidance and abandoning it is misguidance. And the sunnah whose basis is not in the Book of Allah, acting upon it is a virtue and abandoning it is not a sin."
Hadith Referenceالمعجم الأوسط / باب العين / 4011
Hadith Gradingمحدثین:غريب، تفرد به عبد الله بن الرومي ولم يُترجم
Hadith Takhrij«قال الهيثمي: لم يروه عن أبي سلمة إلا عيسى بن واقد تفرد به عبد الله بن الرومي ولم أر من ترجمه «مجمع الزوائد ومنبع الفوائد، ج 1، ص 172»»