(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. (DE)
Reference (DE): Sunan Abi Dawud 2885 (DE)
In-book reference (DE): Book 19, Hadith 1 (DE)
English translation (DE): Book 18, Hadith 2879 (DE)