“Ad-Deen Al-Mu‘aamalah” - not a Hadeeth
7-3-2012 | IslamWeb
Question:
How authentic is the Hadeeth that reads: “Ad-Deen Al-Mu‘aamalah (religion is good dealing)”? May Allaah reward you.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad This is a common saying which means that the essence of religion is good manners when dealing with others. Some people consider it a Hadeeth while others believe it to be a proverb, but we have not found it in any source book of Hadeeth. It seems to be a proverb that signifies the importance of good manners in Islam as confirmed by many Hadeeths of the Prophet Also, the Messenger In another Hadeeth narrated on the authority of Mu‘aawiyah These Hadeeths, as well as many others, show us the great importance and value of good manners in Islam. A Muslim could be a caller to Islam through his manners without uttering a single word, because actions influence people much more than words do. Allaah Knows best.
is His slave and Messenger. , who told us that he was sent to perfect high moral standards. [Maalik in Al-Muwatta’] explained that those who have the best manners will sit nearest to him on the Day of Judgment. [Imaam Ahmad. Al-Haythami: Saheeh (Authentic)] 
the Prophet said that "the best Muslim is he who has the best manners". [Al-Bukhari]