What is the ruling on going ahead and doing something without asking about the ruling on it?
Question

Is the one who could have asked about the ruling on some action, but did not ask, regarded as if proof was established against him? For example, if he is not sure whether doing something is a sin or not, then he decided not to ask about the ruling on it, is there any sin on him if he goes ahead and does that thing, when that thing is a sin? If possible, please refer to scholarly views on this issue, and say which you think is most likely to be correct, if there is no consensus on the matter.
Praise be to Allah.Firstly:
What the Muslim must do is learn before he acts. So it is not permissible for him to go ahead and do something when he does not know the ruling on it. That becomes more important if he is not sure whether that thing is a sin or not.
Allah, may He be exalted, says (interpretation of the meaning):
{And do not pursue that of which you have no knowledge. Indeed, the hearing, the sight and the heart - about all those [one] will be questioned} [al-Isra’ 17:36].
Shaykh Muhammad al-Amin ash-Shinqiti (may Allah have mercy on him) said:
In this verse, Allah, may He be glorified and exalted, forbids pursuing that of which one has no knowledge… That includes speaking without knowledge, or doing some actions about which one has no knowledge. And Allah, may He be glorified and exalted, refers to this meaning in other verses."(Adwa’ al-Bayan  3/682).
Imam al-Bukhari (may Allah have mercy on him) said in his Sahih:
Chapter: Learning before speaking or acting, because Allah, may He be exalted, says (interpretation of the meaning): {So know, [O Muhammad], that there is no god worthy of worship except Allah} [Muhammad 47:19]; thus He began with knowledge.
The scholars are the heirs of the prophets, who left behind a legacy of knowledge. Whoever acquires that knowledge has taken an abundant share, and whoever follows a path seeking knowledge, Allah will make easy for him a path to Paradise.
Allah, may He be glorified and exalted, says (interpretation of the meaning):
{Only those fear Allah, from among His servants, who have knowledge} [Fatir 35:28]
{But none will understand them except those of knowledge} [al-‘Ankabut 29:43]
{And they will say, “If only we had been listening or reasoning, we would not be among the companions of the Blaze”} [al-Mulk 67:10]
{Are those who know equal to those who do not know?} [az-Zumar 39:9].
The Prophet (blessings and peace of Allah be upon him) said: “When Allah wills good for a person, He grants him understanding of religion” and “Knowledge is only acquired through learning.” Abu Dharr said: If you put this sword on here – and he pointed to the back of his neck – then I thought that I could convey a word I heard from the Prophet (blessings and peace of Allah be upon him) before you kill me, I would convey it.
Ibn ‘Abbas said: Be pious scholars of the Lord, possessed of forbearing and understanding. It was said that the pious scholar [rabbani] is the one who starts by teaching people easy issues of knowledge before difficult issues.
Ibn Majah narrated that Anas ibn Malik said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Seeking knowledge is obligatory for every Muslim.”
Ibn ‘Abd al-Barr (may Allah have mercy on him) said:
It was narrated that Ishaq ibn Rahawayh said: Seeking knowledge is obligatory, although there is no soundly-narrated report which says that. But what is meant is that the individual must seek the knowledge of how to do what he needs to do, such as wudu’ and prayer, zakah if he has wealth, and also Hajj and so on…
Abu ‘Umar said: Ishaq meant – and Allah knows best – that regarding the hadith about the obligation to seek knowledge, there are some reservations among the scholars of hadith about its isnad, but its meaning is correct in their view…
Then he narrated with his isnad from ‘Ali ibn al-Hasan ibn Shaqiq that the latter said: I said to Ibn al-Mubarak: What is the thing that the believer cannot do unless he seeks knowledge about it? And what must he learn? He said: He cannot take any action except on the basis of knowledge, and he cannot acquire knowledge unless he asks."(Jami‘ Bayan al-‘Ilm wa Fadlihi  1/52-56).
This is a matter on which the scholars are agreed.
Al-Qarafi (may Allah have mercy on him) said:
Al-Ghazali narrated in Ihya’ ‘Ulum ad-Din that there was consensus on that. Ash-Shafa‘i also narrated in ar-Risalah that it is not permissible for the accountable person to take any action until he knows the ruling of Allah concerning it. So the one who becomes involved in buying and selling must learn the rulings and guidelines that Allah has prescribed with regard to buying and selling. The one who gets involved in renting and hiring must learn what Allah, may He be exalted, has prescribed with regard to renting and hiring. The one who wants to lend or borrow money must learn the rulings that Allah, may He be exalted, has prescribed with regard to lending and borrowing. The one who wants to offer a particular prayer must learn the rulings that Allah, may He be exalted, has prescribed for that prayer. The same applies to purification and all other words and deeds."(Al-Furuq 2/275).
Al-Bukhari (2964) narrated that ‘Abdullah ibn Mas‘ud (may Allah be pleased with him) said:
… One of you will be fine so long as he fears Allah. If he has any doubt about something, he should ask a man who will give him an answer.
Ibn al-Mulaqqin (may Allah have mercy on him) said:
Regarding his words “If he has any doubt about something, he should ask a man who will give him an answer,” what he means is that part of fearing Allah is not doing anything that you are unsure of until you ask someone who has knowledge about that, so that he can give you an answer regarding it."(At-Tawdih  18/81).
Ash-Shatibi (may Allah have mercy on him) said: If one who follows a scholar is faced with some religious issue, he has no option but to ask about it, and that is the general ruling, because Allah did not ask the people to worship Him on the basis of ignorance; rather He asked them to worship Him on the basis of the verse in which He, may He be glorified, says (interpretation of the meaning): {So fear Allah, for it is Allah Who teaches you} [al-Baqarah 2:282]. It is not in the way in which many people interpret this verse; rather, according to the understanding of leading scholars of Arabic language, it means: Allah will teach you about whatever issue you are faced with, so fear Him. It is as if the second thing mentioned (teaching) will lead to the first thing mentioned (taqwa or fear of Allah). So the issue of taqwa (fear of Allah) is connected to the condition, which is that you should acquire knowledge. This means that knowledge comes before actions. There is a great deal of evidence to support this meaning, and this is a matter concerning which there is no dispute among the scholars, so there is no need to discuss it at length."(Al-Muwafaqat  5/283).
Secondly:
If someone is required to ask and learn, but he fails to ask about what he is not sure of with regard to his religion by way of negligence, laziness and following whims and desires, then he is undoubtedly being heedless about his religion and exposing himself to punishment.
Ibn al-Qayyim (may Allah have mercy on him) said:
The one who is able to ask, seek guidance and learn about the truth, but he fails to do that because he is preoccupied with worldly matters, pursuit of leadership, seeking pleasure, making money and so on, is heedless and deserves the punishment, and he is sinning by neglecting what is required of him, which is fearing Allah as much as he can. The ruling in his case is the same ruling as that on others like him who neglect some obligatory duties."(At-Turuq al-Hukmiyyah  1/465).
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) said:
What is required of the individual is not to delay asking people of knowledge, because the more he delays asking, the more he will increase in sin, because Allah, may He be exalted, says (interpretation of the meaning):
{So [O people] ask those who have knowledge, if you do not know} [an-Nahl 16:43].
So what the individual must do is ask first, before taking action. If it so happens that he acts, then becomes uncertain, then he must hasten to ask."(Fatawa Nur ‘ala ad-Darb 8/315).
And Allah knows best.