“Whoever enumerates them” is a qualifying clause, not an independent predicate. The meaning is that Allah has ninety-nine names of such a nature that whoever enumerates them will enter Paradise. This does not preclude His having other names as well. There are many parallels to this in the Arabic language. For example, you may say, “I have ninety-nine dirhams that I have set aside for charity.” This does not preclude your having other dirhams set aside for another purpose. This is well known and undisputed among the scholars.
Indeed, the Sunnah contains evidence that Allah’s names are not confined or limited to any specific number. One example is the report narrated by Muslim in his Sahīh from Aisha—may Allah be pleased with her—who said: “One night, I found that the Messenger of Allah, may Allah’s blessings and peace be upon him, was no longer in bed, so I searched for him. My hand came upon the soles of his feet while he was in the mosque, with both feet upright, and he was saying: ‘O Allah, I seek refuge in Your pleasure from Your wrath, in Your pardon from Your punishment, and in You from You. I cannot fully enumerate Your praise; You are as You have praised Yourself.’”1 Thus, he—may Allah’s blessings and peace be upon him—informed us that he could not fully enumerate Allah’s praise. Had he enumerated all of His names, he would have enumerated all praise of Him.
Another example occurs in the lengthy hadith of intercession, in which he, may Allah’s blessings and peace be upon him, said: “Then Allah will disclose to me forms of praise and beautiful extolment of Him that He has never disclosed to anyone before me.” This hadith indicates that there are forms of praise arising from Allah’s names and attributes with which Allah will inspire His Messenger, may Allah’s blessings and peace be upon him, on that Day. These are undoubtedly distinct from the forms of praise transmitted in the Quran and Sunnah.
Moreover, it is established in al-Musnad and elsewhere, in the hadith of Abdullah ibn Masud