:salam2:
Almighty Allah says in the Holy Qur’an Chapter 16 Verse 116-117: “And do not say about what your tongues assert of untruth, “This is lawful and this is unlawful,” to invent falsehood about Allah . Indeed, those who invent falsehood about Allah will not succeed. [It is but] a brief enjoyment, and they will have a painful punishment.”
Often, we usually say or hear that this is lawful (halaal) and this unlawful (haraam), without realizing that there will be painful punishment if we uttered wrong [false].
So my questions are:
1- To prevent falsehood, do we need certain knowledge? If yes then what kind of knowledge which distinguish what is exactly lawful and unlawful?
2- Or to keep our tongue zipped?
Share your knowledge 
Re: Lawful and Unlawful
**Background:
**
The above verse, in my understanding, is describing the time of persecution before the migration of muslim to Yathrib/Medina. The situation around that time was harsh for muslims in it the makkans not only rejected prophethood of Muhammed, the trustworthy (God be please with him), but also maintained superstitious and egotistical and whimsical rules, and laws of right and wrong in the society. There were particularly those who opposed the teaching of Muhammed (God be pleased with him), because it upset the ruling order of the makkan society, the traditions, and authority, and egos of the businessmen, aristocracy, etc.
Response / Answer
So the matter here is not to prevent others’ ignorance. This Quranic verse points at the nature of knowledge, and the nature of human corruption. It points that the collective justice of a society must be based on correct definition of knowledge, and wisdom. The collective implementation of governing rules should not be based on the desires of the few specially solely to oppose the correct and wiser forms of justice. The verse previous to this refers to the blinded hearts, and deafened ears of such people suggesting that the shallow/evil intent, and rebellious action is a psychological state of mind that leads to sociopathic behavior (based on false perceptions) causing destruction not only of the individual , but also the society as a whole, and these people may enjoy pleasure of their evil actions only for a limited time in Earthly life (at the very best). It is, therefore, best for seeker of wisdom and good/decent intent to abstain from speaking (specifically when in position of authority in a given context) without knowledge about serious legal and ethical matters governing the socioeconomic lives of people.
Re: Lawful and Unlawful
Just a quick reminder when discussing Quranic Verses.
There is a principle in Tafseer the scholars work by:
العبرة بعموم اللفظ لا بخصوص السبب
Meaning: The specific reason for a Verse’s revelation, or the specific event or people it was revealed about, does not restrict its meaning, rather it is to be understood to be as general as the wording allows.
Re: Lawful and Unlawful
Now first lets look at why this Verse was revealed. It was revealed when the disbelievers would make certain things halaal which Allah had made haraam and would make certain things haraam which Allah had made halaal. Tafsir Al-Qurtubi]
The general principle derived from the Verse is that we as Muslims should not follow pursuit and start making things Halal or Haram unless evidence is found in the Qur’aan and Sunnah. Additionally, this Verse teaches scholars Adab when giving Fatwaas.
قال
**ابن وهب ****مالك ****لم يكن من فتيا الناس أن يقولوا هذا حلال وهذا حرام ، ولكن يقولوا إياكم كذا وكذا
(Paraphrase of what Maalik said) One should not say this is Haraam and this is Halaal but should say be careful of such and such when one wants to tell someone to stay away from something. Tafsir Al-Qurtubi]
**Additionally, Ibn Katheer points out that in this Verse is a warning for those who invent innovations and introduce them into Religion. When you say if you do such and such a thing and you will get reward for it, when there is no evidence in the Qur’aan and Sunnah, you are inventing a lie on Allah. Tafsir Ibn Katheer]
So, the answer to your question is yes, unless you are certain that Allah has made something Halaal or Haraam, which can only be confirmed by the Qur’aan and Sunnah, it is best not to say this is Haraam and this is Halaal but you should say be careful of this and avoid it if you think it is impermissible as Maalik would do. And Allah knows best.