Question 507: The Messenger (peace be upon him) said: “Allaah has ninety-nine Names, i.e. one-hundred minus one…” What is the meaning of this Hadeeth? Does this mean we should just memorize Allaah’s Names or act according to them as well?
Answer: First, the mentioned number does not mean that Allaah (Exalted be He) does not have other than these ninety-nine Names, but the meaning is that anyone who memorizes these Names will enter Jannah (Paradise). Thus, the meaning is to inform people that memorizing them will cause admittance to Jannah and not to count all the Names... read more here.