Sahih Bukhari
One-fifth of Booty to the Cause of Allah (Khumus)
Volume: 004 / Book Number: 053 / Hadith Number: 403
Narrated 'Abdullah bin 'Amr:
Allah's Apostle said, "Whoever has (the following) four characteristics will be a pure hypocrite: "If he speaks, he tells a lie; if he gives a promise, he breaks it, if he makes a covenant he proves treacherous; and if he quarrels, he behaves in a very imprudent evil insulting manner (unjust). And whoever has one of these characteristics, has one characteristic of a hypocrite, unless he gives it us."