Is it allowed for a talib ul ilm or a scholar who has some islamic information or knowledge to hide it in fear of being arrested or being watched by authorities?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

If someone knows something from the religion of Allaah, he should teach it to those in need of it and he has to teach others according to his ability, for the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever is asked about a matter of [Islamic] knowledge which he knows but he conceals it, Allaah will bridle him with reins of fire on the Day of Resurrection." [Ahmad, Abu Daawood, Ibn Maajah and At-Tirmithi]

Also, ‘Abdullaah ibn ‘Amr narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Convey from me, even if it is one verse." [Al-Bukhari] The term "convey" is in the imperative form, which mostly means that it is obligatory.

As for going into hiding or altering one's appearance as a scholars, there is nothing wrong with that; so if one fears being killed or being severely harmed in prison, it is permissible to conceal the knowledge he has, as it was narrated that Abu Hurayrah said: “I have retained two kinds of knowledge from the Messenger of Allaah, sallallaahu ‘alayhi wa sallam. I have conveyed one of them to you and if I conveyed the second, then my throat would be cut (i.e. I would be killed).” [Al-Bukhari]

Al-Haafith Ibn Hajar said in Al-Fat-h: "The scholars interpreted this second type of knowledge that he (i.e. Abu Hurayrah) did not convey as the Ahaadeeth that reveal the names of the evil rulers, their conditions and the times when they would rule. Abu Hurayrah used to allude to some of those rulers without expressly stating their names, out of fear for his life. He would say, for example, “I seek refuge in Allaah from the 'head of sixty' or the 'rule of children',” alluding to the caliphate of Yazeed ibn Mu‘aawiyyah, as he became Caliph in the year sixty after Hijrah. Allaah answered the supplication of Abu Hurayrah  as he died a year beforehand."

However, it is more appropriate for a scholar not to fear anyone while conveying the Message of Allaah, The Almighty, as Allaah says (what means): {[Allaah praises] those who convey the messages of Allaah and fear Him and do not fear anyone but Allaah. And sufficient is Allaah as Accountant.} [Quran 33:39]

Moreover, the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said: “The master of the martyrs is Hamzah ibn ‘Abdul-Muttalib and a man who stood up before an unjust ruler and enjoins good and forbids evil and he (the ruler) kills him.” [Al-Haakim: Saheeh (sound); Al-Khateeb; Al-Albaani: Saheeh]

The Prophet, sallallaahu ‘alayhi wa sallam, was asked: “Which is the best type of Jihaad?” He, sallallaahu ‘alayhi wa sallam, said: “A word of truth before an unjust ruler.” [An-Nasaa'i, Ibn Maajah and Ahmad; Al-Albaani: Saheeh]

Having said that, if a scholar is able to serve the interests of the religion in all that he does and consult other scholars and act in accordance with their advice, then this is something good. His teaching people in secret for many years may be better than saying a word over which he is killed and which does not have a positive effect on those he has addressed. It may also be that some sincere, truthful people say a word of truth at the proper time and the ruler takes heed and it puts an end to the evil. The fundamental principle in this regard is that the Islamic Sharee‘ah (divine law) seeks to achieve benefit and complete it and prevent harm and reduce it. The Quran and Sunnah support this. For example, Allaah, The Almighty, says (what means):

·        {…while He has explained in detail to you what He has forbidden you, excepting that to which you are compelled.} [Quran 6:119]

·        {…But whoever is forced [by necessity], neither desiring [it] nor transgressing [its limit], there is no sin upon him.} [Quran 2:173]

·        {…and He has not placed upon you in the religion any difficulty.} [Quran 22:78]

Scholars have derived the following principles from such passages:

-       Necessity makes it permissible to do what is forbidden and to commit the lesser of two evils in order to avoid the greater evil.

-       Preventing harm is given precedence over achieving benefit.

-       [It is better] to serve the greater of two interests.

Shaykh Al-Islam Ibn Taymiyyah said: “The Islamic Sharee‘ah is based on the saying of Allaah, The Almighty (which means): {O you who have believed, fear Allaah as He should be feared and do not die except as Muslims [in submission to Him].} [Quran 3:102], and on the statement of the Prophet, sallallaahu ‘alayhi wa sallam: “…and if I command you to do a thing, then do as much of it as you can.” [Al-Bukhari and Muslim], and on the principle that it is obligatory to seek to achieve benefit and complete it and prevent harm and reduce it, and if there is a conflict of interests, then it is prescribed to serve the greater interest by leaving the lesser interest; and to avoid the greater of two evils by enduring the lesser of them.” [End quote]

Allaah Knows best.