Al-Mundhiri recorded the following chapter in his book Al-Targhib wal-Tarhib:

الترهيب من أن يعلم ولا يعمل بعلمه ويقول ولا يفعله

Discouragement of one who knows but does not act upon his knowledge, and he says what he does not do.

Source: al-Targhīb wal-Tarhīb 1/124

Zayd ibn Arqam reported: The Messenger of Allah, peace and blessings be upon him, said:

اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ عِلْمٍ لاَ يَنْفَعُ وَمِنْ قَلْبٍ لاَ يَخْشَعُ وَمِنْ نَفْسٍ لاَ تَشْبَعُ وَمِنْ دَعْوَةٍ لاَ يُسْتَجَابُ لَهَا

O Allah, I seek refuge in you from knowledge that does not benefit, from a heart that is not reverent, from a soul that is not content, and from a supplication that is not answered.

Source: Ṣaḥīḥ Muslim 2722, Grade: Sahih

Usamah ibn Zayd reported: The Messenger of Allah, peace and blessings be upon him, said:

يُؤْتَى بِالرَّجُلِ يَوْمَ الْقِيَامَةِ فَيُلْقَى فِي النَّارِ فَتَنْدَلِقُ أَقْتَابُ بَطْنِهِ فَيَدُورُ بِهَا كَمَا يَدُورُ الْحِمَارُ بِالرَّحَى فَيَجْتَمِعُ إِلَيْهِ أَهْلُ النَّارِ فَيَقُولُونَ يَا فُلَانُ مَا لَكَ أَلَمْ تَكُنْ تَأْمُرُ بِالْمَعْرُوفِ وَتَنْهَى عَنْ الْمُنْكَرِ فَيَقُولُ بَلَى قَدْ كُنْتُ آمُرُ بِالْمَعْرُوفِ وَلَا آتِيهِ وَأَنْهَى عَنْ الْمُنْكَرِ وَآتِيهِ

A man will be brought on the Day of Resurrection and cast into the Hellfire, and his intestines will pour forth in Hell. He will go around them as a donkey around a millstone. The people of Hell will gather around him and say: What has happened to you? Were you not enjoining good and forbidding evil? He will say: Of course, I used to enjoin good but I did not practice it myself, and I used to forbid evil but I practiced it myself.

Source: Ṣaḥīḥ al-Bukhārī 3094, Grade: Muttafaqun Alayhi

Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said:

رَأَيْتُ لَيْلَةَ أُسْرِيَ بِي رِجَالًا تُقْرَضُ شِفَاهُهُمْ بِمَقَارِيضَ مِنْ نَارٍ فَقُلْتُ يَا جِبْرِيلُ مَنْ هَؤُلَاءِ قَالَ هَؤُلَاءِ خُطَبَاءُ مِنْ أُمَّتِكَ يَأْمُرُونَ النَّاسَ بِالْبِرِّ وَيَنْسَوْنَ أَنْفُسَهُمْ وَهُمْ يَتْلُونَ الْكِتَابَ أَفَلَا يَعْقِلُونَ

I saw some men on the night of my ascension, whose lips were being sheared by scissors of fire. I said: O Gabriel, who are these people? Gabriel said: Preachers from your nation who commanded people to be righteous and they forgot it themselves, yet they recited the Book. Will they not reason?

Source: Musnad Aḥmad 13103, Grade: Sahih

In another narration, the Prophet said:

خُطَبَاءُ مِنْ أُمَّتِكَ الَّذِينَ يَقُولُونَ مَا لَا يَفْعَلُونَ وَيَقْرَءُونَ كِتَابَ اللَّهِ وَلَا يَعْمَلُونَ

Preachers from your nation who said what they did not do, and who recited the Book of Allah and did not act upon it.

Source: Shu’ab al-Imān 1636, Grade: Sahih

Abu Barzah reported: The Messenger of Allah, peace and blessings be upon him, said:

لَا تَزُولُ قَدَمَا عَبْدٍ يَوْمَ الْقِيَامَةِ حَتَّى يُسْأَلَ عَنْ عُمُرِهِ فِيمَا أَفْنَاهُ وَعَنْ عِلْمِهِ فِيمَ فَعَلَ وَعَنْ مَالِهِ مِنْ أَيْنَ اكْتَسَبَهُ وَفِيمَ أَنْفَقَهُ وَعَنْ جِسْمِهِ فِيمَ أَبْلَاهُ

The feet of a servant will not move on the Day of Resurrection until he is asked about his lifetime and how he used it, his knowledge and how he acted upon it, his wealth and from where he acquired it and how he spent it, and his body and how he exhausted it.

Source: Sunan al-Tirmidhī 2417, Grade: Sahih

Mu’adh ibn Jabal reported: The Messenger of Allah, peace and blessings be upon him, said:

لَا تَزُولُ قَدَمَا عَبْدٍ يَوْمَ الْقِيَامَةِ حَتَّى يُسْأَلَ عَنْ أَرْبَعِ خِصَالٍ عَنْ عُمُرُهِ فِيمَا أَفْنَاهُ وَعَنْ شَبَابِهِ فِيمَا أَبْلَاهُ وَعَنْ مَالِهِ مِنْ أَيْنَ اكْتَسَبَهُ وَفِيمَا أَنْفَقَهُ وَعَنْ عَلِمهِ مَاذَا عَمِلَ فِيهِ

The feet of a servant will not move on the Day of Resurrection until he is asked about four matters: his lifetime and how he used it, his youth and how he exhausted it, his wealth and how he earned it and spent it, and his knowledge and how he acted upon it.

Source: al-Mu’jam al-Kabīr 111, Grade: Sahih li ghayrihi

Ibn Mas’ud reported: The Prophet, peace and blessings be upon him, said:

لَا تَزُولُ قَدَمُ ابْنِ آدَمَ يَوْمَ الْقِيَامَةِ مِنْ عِنْدِ رَبِّهِ حَتَّى يُسْأَلَ عَنْ خَمْسٍ عَنْ عُمُرِهِ فِيمَ أَفْنَاهُ وَعَنْ شَبَابِهِ فِيمَ أَبْلَاهُ وَمَالِهِ مِنْ أَيْنَ اكْتَسَبَهُ وَفِيمَ أَنْفَقَهُ وَمَاذَا عَمِلَ فِيمَا عَلِمَ

The son of Adam will not be dismissed from his Lord on the Day of Resurrection until he is questioned about five issues: his life and how he lived it, his youth and how he used it, his wealth and how he earned it and he spent it, and how he acted on his knowledge.

Source: Sunan al-Tirmidhī 2416, Grade: Sahih

Luqman reported: Abu Darda, may Allah be pleased with him, said:

إِنَّمَا أَخْشَى مِنْ رَبِّي يَوْمَ الْقِيَامَةِ أَنْ يَدْعُوَنِي عَلَى رُءُوسِ الْخَلائِقِ فَيَقُولُ لِي يَا عُوَيْمِرُ فَأَقُولُ لَبَّيْكَ رَبِّي فَيَقُولُ لِي مَا عَمِلْتَ فِيمَا عَلِمْتَ

Verily, I fear from my Lord on the Day of Resurrection that I will be called in front of the heads of all creation, saying: O ‘Uwaymir! I will say: At your service, my Lord. He will say: Did you not act upon what you knew?

Source: Shu’ab al-Imān 1712, Grade: Sahih li ghayrihi

Jundub ibn Abdullah reported: The Messenger of Allah, peace and blessings be upon him, said:

مَثَلُ الْعَالِمِ الَّذِي يُعَلِّمُ النَّاسَ الْخَيْرَ وَيَنْسَى نَفْسَهُ كَمَثَلِ السِّرَاجِ يُضِيءُ لِلنَّاسِ وَيَحْرِقُ نَفْسَهُ

The parable of the scholar who teaches people virtue but forgets himself, is that of a lamp giving people light while it burns itself.

Source: al-Mu’jam al-Kabīr 1681, Grade: Sahih

‘Imran ibn Husayn reported: The Messenger of Allah, peace and blessings be upon him, said:

أَخْوَفُ مَا أَخَافُ عَلَيْكُمْ جِدَالُ الْمُنَافِقِ عَلِيمِ اللِّسَانِ

Among what I fear most for you are the debates of hypocrites with a knowledgeable tongue.

Source: Ṣaḥīḥ Ibn Ḥibbān 80, Grade: Sahih

Umar ibn al-Khattab reported: The Messenger of Allah, peace and blessings be upon him, said:

إِنَّ أَخْوَفَ مَا أَخَافُ عَلَى أُمَّتِي كُلُّ مُنَافِقٍ عَلِيمِ اللِّسَانِ

Verily, among what I fear most for my nation is every hypocrite with a knowledgeable tongue.

Source: Musnad Aḥmad 140, Grade: Sahih

In another narration, Umar said:

عَالِمُ اللِّسَانِ جَاهِلُ الْقَلْبِ وَالْعَمَلِ

His tongue is knowledgeable, but his heart and deeds are ignorant.

Source: al-Aḥādīth al-Mukhtārah 215