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 reported it in the Book of Faith (33), and Muslim in the Book of Faith (59), both from the hadith of Ismail bin Jafar, who said, Nafi bin Malik bin Abu Amir, Abu Suhayl, narrated to us, from his father, from Abu Hurairah, and he related it.