Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: The signs of a hypocrite are three: when he speaks, he lies; when he makes a promise, he breaks it; and when he is entrusted, he betrays the trust.
Hadith Referenceاللؤلؤ والمرجان / كتاب الايمان / 38
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 2 كتاب الإيمان: 24 باب علامة المنافق»
Brief Explanation
The signs of hypocrisy mentioned in these ahadith are all related to actions. That is, after becoming a Muslim, hypocrisy is manifested in one's actions. And if hypocrisy is in the heart, meaning that faith is not present at all and one is merely presenting oneself as a Muslim verbally, then that hypocrisy is certainly equal to, or even greater than, disbelief (kufr) and polytheism (shirk). It is stated in the Qur’an: "The hypocrites will be in the lowest depths of the Fire." (Secret)