Where the court gave conflicting jury instructions regarding the specific intent required for assault by a life prisoner (Pen. Code, sec. 4500), the error required reversal. Section 4500 requires proof of malice aforethought, but the court here instructed the jury both under CALJIC 8.11, defining malice aforethought, and under CALJIC 1.22, which defines malice as “a wish to vex, annoy, or injure another person, or an intent to do a wrongful act.” Because malice and malice aforethought are very different mental states, the court should not have given the instruction under CALJIC 1.22. Furthermore, the court erred in giving an unedited instruction under CALJIC 9.00, because the version of the instruction given included an indication that no specific intent was required for assault, in direct contradiction of the malice aforethought requirement under section 4500. The errors were not harmless beyond a reasonable doubt and thus required reversal.