The Book of Asceticism · Hadith 105 (#Ḥadīth #17)

إبراهيم بن أبي البلاد عن أبيه عن أبي عبد الله عليه السلام قال: لو علم الله شيئا أدنى من أف لنهى عنه وهو أدنى العقوق ومن العقوق ان ينظر الرجل إلى أويه يحد إليهما.

18.Ibrāhīm ibn Abī al-Bilād narrated from his father, from Abū ʿAbdillāh who said, “If Allah knew [human beings capable of using] anything less than ‘uff’ [against their parents], He would have forbidden it, and that is the smallest form of undutifulness. Another form of undutifulness is for a man to look at his parents with a stern [and angry] stare.”

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).