The Prophet ﷺ said, "The signs of a hypocrite are three. When he speaks, he lies. When he makes a promise, he breaks it. When he is entrusted with something, he betrays the trust."
عن النبي ﷺ قال: آية المنافق ثلاث: إذا حدث كذب، وإذا وعد أخلف، وإذا اؤتمن خان.
Bukhari related it in al-Adab (6095), and Muslim in al-Iman (59:107), both through Ismail bin Jafar, who said, Nafi bin Malik bin Abu Amir Abu Suhayl narrated to us, from his father, from Abu Hurairah, who mentioned it.