12 And I give unto them a name that never shall be blotted out, except it be through transgression.
At the end of his words, in Mosiah 5:11, he says:
11 And I would that ye should remember also, that this is the name that I said I should give unto you that never should be blotted out, except it be through transgression; therefore, take heed that ye do not transgress, that the name be not blotted out of your hearts.Note he even mentions that he had already said he would give them a name.