I asked a famous scholar of the present time about the ruling on Mawlid celebrations and the evidence for their legitimacy; he answered that they are among the unrestricted public interests.

Eid Abbasi : I asked a famous scholar of the present time about his opinion on holding Mawlid celebrations, and about the legal evidence for their permissibility; he answered that the evidence for them is that they are among the unrestricted public interests; meaning: that there is a benefit for the Muslims in them, even if the Salaf did not do them; so what is the answer to this? Then what is the ruling...?

The Shaykh : I do not know if the one who gave this answer knows what the unrestricted public interests are, and when they become legitimate interests, and I suspect that he does not know what a legitimate unrestricted public interest is. I give as an example: the one who claims the legitimacy of these Mawlid celebrations on the grounds that they are unrestricted public interests and that they realize a benefit for the Muslims is like the one who legislates all these earthly laws that did not descend from the Lord of the Worlds. Undoubtedly, all people, whether disbelievers, open sinners, or wicked, agree that there are benefits in these laws. Undoubtedly, we are with them in that there are benefits in these laws. But where was the Lord of the Worlds before these laws? Did He not bring a law from Himself, to which no falsehood comes from before it or from behind it?
The answer: Certainly, He brought it to us. So when we claim that there are benefits for the Muslims in these newly invented matters, that means one of two things: either our religion is not complete—and this is, of course, disbelief in the Qur'an—, or these laws and these religious innovations are not from Allah in any way, and this is the truth about which there is no doubt.
Unrestricted public interests are those in which new events and matters arise among people, and they are compelled to adopt them because they actually realize a benefit for them without any contradiction of the Shari'ah. But this, too, is not sufficient; rather, it is necessary that this unrestricted public interest did not have its cause present during the time of the Prophethood and the Message, but rather this cause for adopting it occurred afterwards. This research is, in reality, among the pearls of Shaykh al-Islam Ibn Taymiyyah (may Allah have mercy on him) in his book "Iqtida' al-Sirat al-Mustaqim Mukhalafat Ahl al-Jahim" (Following the Straight Path: Opposing the People of the Hellfire); because he speaks about newly invented matters with words containing great detail. He says: Everything that occurred after the Messenger (peace and blessings be upon him) that can be described as good or as containing a benefit must be one of two things: either the cause for adopting it was present in his time (peace be upon him), or the cause was not present in his time but rather occurred afterwards.
In the first case, when the cause for adopting it is present, it is not permissible to adopt it at all; for the reason we mentioned, that the Shari'ah is complete. An example of this is what is agreed upon to this day, even though it is not in the Shari'ah: leaving off the adhan (call to prayer) in the two Eid prayers. To this day, there is no adhan for the Eid prayers. This was the case in the time of the Messenger (peace and blessings be upon him), unlike the five daily prayers, as is well known. If someone were to say: "My brother, there is a benefit in the adhan for the Eid prayers, which is alerting people to the arrival of the time," we would say to them, based on our understanding of the words of Ibn Taymiyyah, which is a truth without doubt: this expected benefit of this adhan was present in the time of the Messenger (peace and blessings be upon him), and the cause for the legitimacy of this adhan was present. Did anything new occur? The answer will be one thing: No, there is no difference in this regard. Whether we call the adhan now, the claimed benefit is present, or if the adhan was called in the time of the Messenger (peace and blessings be upon him), the benefit is present. So how did the Messenger (peace and blessings be upon him) not legislate this from Allah, naturally? Because Allah is the one who truly legislates. How did He not legislate this adhan, when it is supposed that the call is legislated for the benefit it realizes? This example of the "good innovation" or the "unrestricted public interest" shows that it is not such if the cause for adopting it was present in the time of the Messenger (peace and blessings be upon him). This is clear, if Allah wills, to everyone. And we apply this analogy to all—or most, so as not to exaggerate in speech—most of the religious innovations that have spread in the Islamic world today, unfortunately. All these innovations for which it is said: "My brother, what is wrong with it? My brother, it has a benefit?" All of that, if it had a benefit, would have been legislated in the time of the Messenger (peace and blessings be upon him); because the cause for its legislation was present. This is the first category: either the cause was present in the time of the Messenger (peace and blessings be upon him) and it was not adopted as required; then this is misguidance, and every misguidance is in the Fire.
Or, the cause occurred after the Messenger (peace and blessings be upon him) and was not present. Here comes a new research from the words of Ibn Taymiyyah. It appears at first glance that, since the cause was not in the time of the Messenger (peace and blessings be upon him) but rather occurred afterwards, it should be said: "By Allah, since the cause was found afterwards, and adopting its requirement, which is the benefit, does not imply attributing a deficiency to the Shari'ah as we mentioned in the first case." It appears at first glance that Ibn Taymiyyah said: Is this innovation or this unrestricted public interest to be adopted?
The answer: No, detail is necessary. Shaykh al-Islam Ibn Taymiyyah (may Allah have mercy on him) said: It is looked at; if the cause that occurred afterwards was not present because of the Muslims' negligence in adopting the rulings of the religion, then it is a rejection—also. Every religious innovation is misguidance, and every misguidance is in the Fire, even if it realizes a benefit; because the benefit would have been realized by another way taken from the Shari'ah itself. An example, for instance: in our reality today, taxes are imposed in many different types and numerous names. These taxes, without doubt, are intended for what? Filling the state treasury so that it can carry out the interests of the nation. Yes, it is very clear that there is a benefit and a utility in this. But this benefit, which is imposing taxes, was not in the time of the Messenger (peace and blessings be upon him). What necessitated adopting it? Our negligence in applying our Shari'ah. There are sources of revenue for zakah, sources for collecting funds, including zakah, and many things explicitly mentioned in the Qur'an and the Sunnah. These have been neglected today absolutely. So it became an urgent necessity for those who do not adopt Islam as a Shari'ah to invent new means to realize what they missed due to their neglect of the legitimate means and causes. This is our research in the issue of the Mawlid.
Is the Mawlid an unrestricted public interest?? We say: Was the cause for acting upon this benefit present in the time of the Messenger (peace and blessings be upon him) or not? If they say: It was present; then why was the celebration not legislated? And if they say: It was not present, but rather occurred after the Messenger (peace and blessings be upon him) by three hundred years and more? We ask them: Did this occurrence happen because of the Muslims' adherence to their religion and the Sunnah of their Prophet, or because of their turning away from it? Here it remains a precise and very precise scientific research. Can they say: No, this is because of their adherence to the Sunnah? If that were the case, the earliest people of the Sunnah, the Companions of the Messenger, the Tabi'un, and those after them would have been more deserving of it; because they were, without doubt, more eager to adhere to the Sunnah and to good than we are. So, nothing remains but that this happened because of the Muslims' turning away from adhering to the Sunnah.
Finally: I remind you of something I have researched on this occasion, and more than one occasion. I said: We have a celebration for the birth of the Messenger (peace and blessings be upon him), but there is a great difference between our celebration and theirs. Our celebration is a recommended practice based on the words of the Messenger (peace and blessings be upon him), and their celebration is a religious innovation against the words of the Messenger (peace and blessings be upon him). It was said to the Messenger (peace and blessings be upon him): What do you say about fasting on Monday? He said: . So the celebration of the Messenger (peace and blessings be upon him) for his birth is by fasting on Monday. Every week is a celebration, not every year. Every week is a celebration, and it is a prescribed celebration, not every year once, and a celebration that is not prescribed.
"So this difference between us is sufficient *** And every vessel emits what is in it."