The people of the pre-Islamic era used to eat certain things and abstain from others out of revulsion. Then Allah Almighty sent His Prophet ﷺ, revealed His Book, made lawful what He permitted, and forbade what He prohibited. So whatever He made lawful is lawful, whatever He forbade is forbidden, and whatever He remained silent about is pardoned.Then he recited, "Say, I do not find within that which was revealed to me anything forbidden" [Anam 6:145], to the end of the verse.
حدثنا محمد بن داود بن صبيح حدثنا الفضل بن دكين حدثنا محمد يعني ابن شريك المكي عن عمرو بن دينار عن أبي الشعثاء
كان أهل الجاهلية يأكلون أشياء ويتركون أشياء تقذرا فبعث الله تعالى نبيه ﷺ وأنزل كتابه وأحل حلاله وحرم حرامه فما أحل فهو حلال وما حرم فهو حرام وما سكت عنه فهو عفو وتلا {قل لا أجد فيما أوحي إلي محرما} إلى آخر الآية
Sourcing, its isnad is sahih. Hakim narrated it, 4/115, from the hadith of Fadl bin Dukayn through this route, and he graded it sahih, and Dhahabi agreed with him.