Knowledge in the context of hiding can be of two types:

One which relates to religious matters and the second one which relates to wordly matters.

As for the first type, Quran has made clear to not conceal any knowldege which relates to revelation of God. People who do such a deed have been vehemently cursed by Quran. And this warning appears to be very severe for religious scholars specially.

إِنَّ الَّذِينَ يَكْتُمُونَ مَا أَنزَلْنَا مِنَ الْبَيِّنَاتِ وَالْهُدَى مِن بَعْدِ مَا بَيَّنَّاهُ لِلنَّاسِ فِي الْكِتَابِ أُولَـئِكَ يَلعَنُهُمُ اللّهُ وَيَلْعَنُهُمُ اللَّاعِنُونَ

“Those who conceal the clear proofs and the guidance We have revealed [in this matter] even though We had openly proclaimed them for these people in our Book it is they who shall be cursed by God and cursed by those who curse“. (Quran 2:159)

(Excerpt from Quranic Exegesis)

(English Rendering by Dr. Shehzad Saleem)

There is one other domain to this aspect as well; Exhorting one another to the truth and exhorting one another to remain steadfast on it (tawasi bi a-haqq wa tawasi bi al-sabr) is one of the permanent requirements of faith:

وَالْعَصْرِ إِنَّ الْاِنْسَانَ لَفِيْ خُسْرٍ إِلَّا الَّذِيْنَ أَمَنُوْا وَعَمِلُوا الصَّالِحَاتِ وَتَوَاصَوْا بِالْحَقِّ وَتَوَاصَوْا بِالصَّبْرِ

Time bears witness that these people shall definitely be in a state of loss. Yes! except those who accepted faith and did righteous deeds and exhorted one another to the truth and exhorted one another to remain steadfast on it. (Quran 103:1-3)

Exhorting one another to the truth and exhorting one another to remain steadfast on it relates to one’s immediate surroundings. This is an obvious requirement of accepting the truth and is also termed as amr bi al-maruf and nahyi ‘an al-munkar by the Quran, implying the fact that a person should exhort those in his surroundings to what is maruf (good) according to human nature and intellect and forbid them from what is munkar (evil) according to it:

وَالْمُؤْمِنُونَ وَالْمُؤْمِنَاتُ بَعْضُهُمْ أَوْلِيَاء بَعْضٍ يَأْمُرُونَ بِالْمَعْرُوفِ وَيَنْهَوْنَ عَنِ الْمُنكَرِ

And believers, both men and women, are friends to one another. [They] enjoin what is good and forbid what is evil. (Quran 9:71)

Therefore, for the religious matters, the above mentioned points need to be kept in mind and any intentional failure in this regard will definitely make one accountable in front of Allah.

The second type of knowledge i.e. the worldly knowledge can only become a source of accountability for the person if they are hiding it despite the fact they were ethically responisble to disclose it e.g. A teacher hiding knowledge when he was made responsible to teach it because this falls in usurping rights of one’s students or a religious scholar hiding knowledge of religion from his audience (As per Quran 7:33).

There is one other domain to this aspect as well; If emotions, vested-interests and biases try to divert a person from justice in some worldly or religious matter, his faith requires of him not only to adhere to justice but also if his witness is required in these matters, he should do so even if it puts his life in danger. He should uphold the truth by saying what is the truth and surrendering before it. He should adhere to justice and bear witness to it, and stick to it in his beliefs and deeds. This is called qiyam bi al-qist (adhering to justice), and in the Quran it is referred to in the following words:

يَا أَيُّهَا الَّذِينَ آمَنُواْ كُونُواْ قَوَّامِينَ بِالْقِسْطِ شُهَدَاء لِلّهِ وَلَوْ عَلَى أَنفُسِكُمْ أَوِ الْوَالِدَيْنِ وَالأَقْرَبِينَ إِن يَكُنْ غَنِيًّا أَوْ فَقَيرًا فَاللّهُ أَوْلَى بِهِمَا فَلاَ تَتَّبِعُواْ الْهَوَى أَن تَعْدِلُواْ وَإِن تَلْوُواْ أَوْ تُعْرِضُواْ فَإِنَّ اللّهَ كَانَ بِمَا تَعْمَلُونَ خَبِيرًا

Believers, adhere to justice by bearing true witness before God, even though it be against yourselves, your parents, or your kinsfolk. If someone is rich or poor, God knows better about them both. So do not be led by base-desires, lest you swerve from the truth. If you distort your testimony or decline to give it, you should remember that God is well aware of all your deeds. (Quran 4:135)

يَا أَيُّهَا الَّذِينَ آمَنُواْ كُونُواْ قَوَّامِينَ لِلّهِ شُهَدَاء بِالْقِسْطِ وَلاَ يَجْرِمَنَّكُمْ شَنَآنُ قَوْمٍ عَلَى أَلاَّ تَعْدِلُواْ اعْدِلُواْ هُوَ أَقْرَبُ لِلتَّقْوَى وَاتَّقُواْ اللّهَ إِنَّ اللّهَ خَبِيرٌ بِمَا تَعْمَلُونَ

Believers, adhere to justice by bearing witness for God. Your animosity for some people should not induce you to turn away from justice. Be just; this is nearer to piety. Have fear of God; indeed, God is well aware of all your deeds. (Quran 5:8)

Therefore, All such ahadith [Foot Note 1] pointing toward the importance of sharing knowledge and condemning concealment of knowledge need to be understood in the context as detailed above.

_____________

[Foot Note 1]:

https://sunnah.com/tirmidhi:2649

https://sunnah.com/abudawud:3658

https://sunnah.com/ibnmajah:261

https://sunnah.com/ibnmajah:265

https://sunnah.com/ibnmajah:266