It is narrated from Ubaidullah bin Abi Ja'far that the Messenger of Allah, peace and blessings be upon him, said: "The one among you who is the boldest in giving fatwas is the one who is the boldest in entering the Hellfire."

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Whoever says something that is not in the Book of Allah, nor from the sayings of the Messenger, and says it from his own opinion, then he does not know how much he will have to bear its consequences when he meets Allah, the Mighty and Majestic.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him): If a person is given a fatwa without evidence or proof, then its sin is upon the one who gave the fatwa.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Whoever gives a fatwa without knowledge or understanding, its sin will be upon him (the one who gave the fatwa).

It is narrated from Maymun bin Mehran that when any dispute came to Sayyiduna Abu Bakr (may Allah be pleased with him), he would refer to the Holy Qur'an, and if he found its solution therein, he would decide accordingly. If he did not find the matter in the Book of Allah and had any knowledge from the Messenger of Allah (peace and blessings be upon him) regarding that matter, he would decide according to that. And if he did not remember anything himself, he would go out and say to the other Companions: "Such and such a matter has come to me; do any of you have any knowledge from the Messenger of Allah (peace and blessings be upon him) regarding this matter?" Sometimes, some people would unanimously inform him of the decision of the Prophet (peace and blessings be upon him) in this regard. Upon this, Sayyiduna Abu Bakr (may Allah be pleased with him) would say: "Thanks be to the One who has created among us such people who remember the sayings of their Prophet (peace and blessings be upon him)." And if they too did not find any Sunnah of the Messenger (peace and blessings be upon him), then he would gather selected noble persons and consult them, and whatever they all agreed upon, he would issue the decision accordingly.

Abu Sahl (Nafi’ bin Malik al-Asbahi) said: My wife had vowed to perform i’tikaf for three days in Masjid al-Haram. I asked Umar bin Abdul Aziz about this, and at that time Ibn Shihab al-Zuhri was also present with him. I said: Is fasting also obligatory upon her? Ibn Shihab said: There is no i’tikaf without fasting. Umar bin Abdul Aziz said to him: Is anything like this narrated from the Messenger of Allah (peace be upon him)? Zuhri said: No. He asked: Did our master Abu Bakr (may Allah be pleased with him) say anything like this? He said: No. He asked: So did our master Umar (may Allah be pleased with him) say this? He said: No. He asked: Did our master Uthman (may Allah be pleased with him) say this? He replied: No. So Umar bin Abdul Aziz said: In my opinion, fasting is not obligatory upon her. After that, I left from there and met Tawus and Ata bin Abi Rabah, so I asked them about this issue as well. Thus, Tawus replied that our master Abdullah bin Abbas (may Allah be pleased with them both) did not consider fasting necessary in such a case (i.e., in i’tikaf of vow), unless she also intended to fast. Ata said: This is also my opinion.

It is narrated from Abu Nadrah (Munzir bin Malik) that when Abu Salamah came to Basra, I and Sayyiduna Hasan (may Allah be pleased with him) went to him. He asked Sayyiduna Hasan (may Allah be pleased with him): "Are you Hasan? In Basra, there is no one I wished to meet more than you, and this is because I have learned that you issue fatwas based on your own opinion. (Therefore, listen:) Do not issue any fatwa based on your own opinion. If there is something in the Sunnah of the Messenger of Allah (peace and blessings be upon him) or in the Holy Qur'an, then mention only that."

It is narrated from Jabir bin Zaid that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) met him while performing Tawaf, so he said: Abu Sha’tha! You are among the jurists of Basra, so give fatwa only according to the explicit text of the Qur’an and the established Sunnah. If you act contrary to this, you will destroy yourself and destroy others as well.

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: There was a time upon us when neither did we give fatwas nor were we worthy of it, but Allah the Exalted decreed otherwise and you see the state we have reached. From today onwards, whoever is faced with any matter should decide according to what is present in the Book of Allah, the Mighty and Majestic. And if such a matter arises which is not found in the Book of Allah, then he should decide as the Messenger of Allah (peace and blessings be upon him) decided. Then if such an issue comes up which is neither in the Book of Allah nor did the Messenger of Allah (peace and blessings be upon him) make a decision about it, then he should decide as the pious predecessors decided, and he should not say, "I fear" or "this is my opinion," because the unlawful is clear and the lawful is also evident, and between the lawful and unlawful are some doubtful matters. So, leave that in which you have doubt and adopt that in which there is no doubt or suspicion.

It is narrated from Ubaidullah bin Abi Yazid that when a matter was asked of Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both), if it was mentioned in the Holy Qur'an, he would inform of it. If it was not in the Noble Qur'an but found in the hadith of the Messenger of Allah (peace and blessings be upon him), he would inform of it. And if it was not in the hadith either, he would look at the verdicts of Sayyiduna Abu Bakr and Umar (may Allah be pleased with them both). If he did not find the matter there either, then he would express his own opinion regarding it.