Goddess Parvati inquired about Omkareshwar Ling, and Lord Shiva related a story from Kashi Khand, Chapter 73. Kashi is one such holy place that is acquired by many such Shiv Lings.
Lord Brahma once performed terrible penance for several long years, and huge or extremely powerful energy emerged from underneath, penetrating the ground, and disseminating pure light all around. Lord Brahma witnessed divine energy that represented the three Vedas (Rig, Yajur, and Sam Veda) in the shape of a divine Ling.
Lord Brahma perceived the energy of OM, which rules the entire cosmos, in that heavenly light, which stood for Akaar, Ukaar, and Makar. A monster with four horns, seven hands, and two heads appeared to Lord Brahma. He also perceived a celestial force that included all of the Vedas, Puranas, and the five Brahms (Akaar, Ukaar, Makaar, Naad, and Bindu).
The Panchakshara Ling (Panch+Akshar, which stands for the five letters given in the headings above) so mesmerized Lord Brahma that he began praising Lord Shiva, whom he could see standing in front.
The laudations and eulogies that Lord Brahma offered to Lord Shiva in reverence have been recounted in great detail by Kashi Khand. Lord Shiva bestowed a celestial blessing to Lord Brahma in response to the latter’s requests.
Lord Brahma wanted Omkareshwar to be the name of the Shiv Ling, which had manifested as Divine energy, and that Lord Shiva should always reside there. Accordingly, Lord Shiva granted permission and decreed that the Shiv Ling would be known as Shiva Panchayatan and serve as a representation of Akaar, Ukaar, Makaar, Naad, and Bindu.
The fear of reincarnation will go from the devotee who worships Omkareshwar and takes a holy bath in the Matsyodari Teerth. The advantages of doing Ashwa are available to everybody who worships the idol of Lord Shiva.
Yagna for Medha. Worshiping Omkareshwar is akin to saying one lakh Rudra Japam and to visiting every Shiv Ling in existence.
If someone dies anywhere other than Kashi, they will still reach Mukti if they are an Omkareshwar devotee. Lord Shiva assured Lord Brahma that he would be successful in his task of creating humans thanks to Omkareshwar’s radiance. Lord Shiva left the Ling after bestowing all the blessings onto Lord Brahma.
Five Shiv Lings have formerly stood in for the Shiva Panchayatan, i.e. Bindu Ling, Makareshwar, Omkareshwar, Akaareshwar, and Naadeshwar. Akaareshwar, Omkareshwar, and Makaareshwar are the only Lings left as of right now.
Nadeshwar and Kapileshwar are other names for Omkareshwar Ling. On the banks of Matsyodari Teerth, where the Ganges used to converge during the rainy season, was said to be the location of Omkareshwar Ling. A bath in Matsyodari Teerth and prayers to Lord Omkareshwar on Ashtami and Chaturdasi days, according to Kashi Khand (Chapter 73), can purify the devotee of all sins. A person who offers prayers at the Lord Omkareshwar temple is extremely fortunate and will enter paradise. When they witness their descendant worshipping at the temple above, his ancestors experience bliss.