The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wa'l-Adab)
Muslim :: Book 32 : Hadith 6204
Abu Huraira reported that a person said: Allah's Messenger, I have relatives with whom I try, to have close relationship, but they sever (this relation). I treat them well, but they treat me ill. I am sweet to them but they are harsh towards me. Upon this he (the Holy Prophet) said: If it is so as you say, then you in fact throw hot ashes (upon their faces) and there would always remain with you on behalf of Allah (an Angel to support you) who would keep you dominant over them so long as you adhere to this (path of righteousness).