Abu Dawud
Zakat
Book Number: 003 / Hadith Number: 1690
Narated By AbdurRahman ibn Awf : I heard the Apostle of Allah (pbuh) say: Allah the Exalted has said: I am Compassionate, and this has been derived from mercy. I have derived its name from My name. If anyone joins it, I shall join him, and if anyone cuts it off, I shall cut him off.