Sahih Muslim
The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wal-Adab)
Book Number: 032 / Hadith Number: 6273
'A'isha, the wife of Allah's Apostle (may peace be upon him), reported that Allah's Messenger (may peace be upon him) said: 'A'isha, verily Allah is kind and He loves kindness and confers upon kindness which he does not confer upon severity and does not confer upon anything else besides it (kindness).