The signs of a hypocrite are three

even if he fasts and prays and claims to be a Muslim

عَنْ أَبِي هُرَيْرَةَ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ عَلَامَاتِ الْمُنَافِقِ ثَلَاثَةٌ وَإِنْ صَامَ وَصَلَّى وَزَعَمَ أَنَّهُ مُسْلِمٌ إِذَا حَدَّثَ كَذَبَ وَإِذَا وَعَدَ أَخْلَفَ وَإِذَا اؤْتُمِنَ خَانَ

33 صحيح البخاري كتاب الإيمان باب علامة المنافق

59 صحيح مسلم كتاب الإيمان باب بيان خصال المنافق

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said, “The signs of a hypocrite are three, even if he fasts and prays and claims to be a Muslim: when he speaks he lies, when he gives a promise he breaks it, and when he is trusted he is treacherous.”

Source: Sahiḥ al-Bukhari 33, Sahiḥ Muslim 59