If climbing up to the cave of Hira’ is done with the intention of drawing closer to Allaah, then this is an innovation for which there is no shar’i evidence. The basic principle concerning acts of worship is tawqeef i.e., adhering only to that which is proven in the Qur’aan and saheeh Sunnah, so it is not prescribed to do any act of  worship except that which has been prescribed by Allaah, may He be exalted, or by His Messenger (peace and blessings of Allaah be upon him). 

If it is done with the intention of taking a look and exploring it, there is no reason why it should not be done, unless a person fears that ignorant people may misinterpret his climbing up and take him as an example, and think that climbing up to it is an act of worship that brings one closer to Allaah. 

Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said: With regard to visiting mosques in Makkah apart from al-Masjid al-Haraam, such as the mosque that is at the foot of al-Safa or the mosque on the slope of Mount Abu Qabees and other mosques that were built in places where the Prophet (peace and blessings of Allaah be upon him) and his companions went, there is no evidence for that in the Sunnah, and none of the imams encouraged that. Rather what is prescribed is to go to al-Masjid al-Haraam in particular, and to visit places where rituals of Hajj are done, such as ‘Arafah, Muzdalifah, al-Safa and al-Marwah. Similarly, it is not part of the Sunnah of the Messenger of Allaah (peace and blessings of Allaah be upon him) to visit any of the mountains and sites around Makkah apart from the sites of ‘Arafah, Muzdalifah and Mina, such as Mount Hira’ and the mountain at Mina where it is said that there is qubbat al-fida’ and so on. It is not part of the Sunnah of the Messenger of Allaah (peace and blessings of Allaah be upon him) to visit any of these sites, rather that is an innovation (bid’ah). End quote from Majmoo’ Fataawa Ibn Taymiyah (26/144). 

And he (may Allaah have mercy on him) stated that the Prophet (peace and blessings of Allaah be upon him) did his fourth ‘Umrah with the Farewell Pilgrimage, and hordes of Muslims performed Hajj with him, and no one stayed behind and did not do Hajj with him expect those whom Allaah willed. 

In all of that, neither he nor any of his companions went to the cave of Hira’ or visited it, or any of the other sites around Makkah. There was no worship except in al-Masjid al-Haraam, between al-Safa and al-Marwah, and in Mina, al-Muzdalifah and ‘Arafaat. 

Then after he was gone, neither the Rightly-Guided Caliphs nor others among the earlier generations, went to the cave of Hira’ to pray and supplicate there. 

It is well known that if this was something prescribed and recommended for which Allaah gives reward, the Prophet (peace and blessings of Allaah be upon him) would have known it best of all people, and he would have taught it to his companions, and his companions would have known it better and been more keen to do it than those who came after them. As they did not pay any attention to any such matters, it is known that it is an innovation, which they did not regard as an act of worship and obedience that draws one closer to Allaah, so whoever regards it as an act of worship and obedience that draws one closer to Allaah has followed a path other than their path and has prescribed in Islam something which Allaah has not permitted. End quote from Iqtida’ al-Siraat al-Mustaqeem, p. 425. 

The Scholars of the Standing Committee for Issuing Fatwas were asked: There are accidents in which some pilgrims fall whilst climbing Jabal al-Noor and when coming down from the cave. Some people have suggested building stairs leading to the site of the cave and enclosing it on all sides with a metal grate which will prevent people from entering it except from the designated route for climbing and descending. 

They replied: 

Climbing up to this cave is not one of the rituals of Hajj or Sunnahs of Islam, rather it is an innovation and is one of the things that lead to shirk or associating others with Allaah. Based on that, people should be prevented from climbing up to it; no stairs should be built and it should not be made easier to climb up to it, in accordance with the words of the Prophet (peace and blessings of Allaah be upon him): “Whoever introduces anything into this matter of ours that is not part of it will have it rejected.” Saheeh – agreed upon. More than fourteen centuries have passed since the Revelation came down and Islam appeared, and we do not know of any of the caliphs who succeeded the Messenger of Allaah (peace and blessings of Allaah be upon him) or his companions or the imams of the Muslims who took charge of the holy sites who did that at any time during this long history. All goodness is in following them and their way, in order to draw closer to Allaah and in accordance with the way of His Messenger (peace and blessings of Allaah be upon him), and so as to ward off the means that may lead to shirk. End quote. 

Fataawa al-Lajnah al-Daa’imah (11/359). 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: Some people go to the cave of Hira’ thinking that this is Sunnah, when it is not. The cave of Hira’ is a cave in which the Prophet (peace and blessings of Allaah be upon him) used to worship Allaah for several nights before his Prophethood began and the Revelation came to him when he was in this cave, but the Prophet (peace and blessings of Allaah be upon him) did not go back to it after that, and the Sahaabah did not visit it. There is another cave to which some people go, thinking that this is an act of worship. That is the cave of Thawr in which the Messenger (peace and blessings of Allaah be upon him) hid during the Hijrah. But visiting it is not Sunnah and is not an act of worship that brings one closer to Allaah, may He be glorified and exalted. But if a person climbs up Mount Hira’ or Mount Thawr in order to take a look only, without seeking to draw closer to Allaah by doing this climb, should he be denounced? The answer is that he should not be denounced, but the one who goes there to worship Allaah and draw closer to Him should be denounced. End quote from al-Liqa’ al-Shahri (65/3). 

And Allaah knows best.