Is this a Hadith?
من تهاون بالأدب عوقب بحرمان السنن، ومن تهاون بالسنن عوقب بحرمان الفرائض، ومن تهاون بالفرائض عوقب بحرمان المعرفة
Imam Bayhaqi (rahimahullah) has recorded this narration as the statement of Imam ‘Abdullah ibn Al Mubarak (rahimahullah). I have not come across this as a Hadith of Rasulullah (sallallahu ‘alayhi wa sallam).
(Shu’abul Iman, Hadith: 3017)
A similar narration has also been attributed to Imams Ruwaym and Abu ‘Ali Ad-Daqqaq (rahimahumallah). See here.
Whoever becomes unmindful of etiquette, will be punished by abandoning Sunnah deeds and whoever becomes unmindful and negligent of Sunnah deeds will be punished by abandoning compulsory deeds and whoever is unmindful of obligatory deeds will be punished by being deprived of recognising [Allah Ta’ala].
See this link for a detailed article on the importance of etiquette.
And Allah Ta’ala Knows best.
Answered by: Moulana Suhail Motala
Approved by: Moulana Muhammad Abasoomar