hadith 41 & 42
Do not consider any act of kindness insignificant, even meeting your brother with a cheerful face.
Muslim
The Prophet (peace_be_upon_him) said: O community of people, who believed by their tongue, and belief did not enter their hearts, do not back-bite Muslims, and do not search for their faults, for if anyone searches for their faults, Allah will search for his fault, and if Allah searches for the fault of anyone, He disgraces him in his house.
Abu Dawud, Book 41, Number 4862.
Muslim
The Prophet (peace_be_upon_him) said: O community of people, who believed by their tongue, and belief did not enter their hearts, do not back-bite Muslims, and do not search for their faults, for if anyone searches for their faults, Allah will search for his fault, and if Allah searches for the fault of anyone, He disgraces him in his house.
Abu Dawud, Book 41, Number 4862.