I said, "Messenger of Allah, tell me what is lawful for me and what is forbidden to me."The Prophet ﷺ looked up and then down, then said, "Righteousness is what the soul finds rest in and the heart feels at ease with, and sin is what the soul does not rest in and the heart does not feel at ease with, even if those who give legal opinions tell you otherwise. Do not go near the flesh of the domesticated donkey, nor any predator with fangs."
قلت: يا رسول الله، أخبرني بما يحل لي، ويحرم علي، قال: فصعد النبي ﷺ وصوب في النظر، فقال: البر ما سكنت إليه النفس، واطمأن إليه القلب، والإثم ما لم تسكن إليه النفس، ولم يطمئن إليه القلب، وإن أفتاك المفتون وقال: لا تقرب لحم الحمار الأهلي، ولا ذا ناب من السباع.
Ahmad (17742) narrated it from Zayd bin Yahya Dimashqi, who said, "Abdullah bin Ala told us, who said, 'I heard Muslim bin Mishkam say, "I heard Khushani say," and then he mentioned it.'" Its isnad is sahih. Tabarani (22/219) also narrated it from Abdullah bin Ahmad, from his father, in abridged form.