(1) باب مَا جَاءَ فِي تَعْلِيمِ الْفَرَائِضِ
Narrated Abdullah ibn Amr ibn al-'As:
The Prophet (ﷺ) said: Knowledge has three categories; anything else is extra; a precise verse, or an established sunnah (practice), or a firm obligatory duty. (AR)
Reference (AR): Sunan Abi Dawud 2885 (AR)
In-book reference (AR): Book 19, Hadith 1 (AR)
English translation (AR): Book 18, Hadith 2879 (AR)