Some sources emphasize that executions of apostates have been "rare in Islamic history". According to historian Bernard Lewis, in "religious polemic" in the "early times" of Islam, "charges of apostasy were not unusual", but the accused were seldom prosecuted, and "some even held high offices in the Muslim state". Later, "as the rules and penalties of the Muslim law were systematized and more regularly enforced, charges of apostasy became rarer." When action was taken against an alleged apostate, it was much more likely to be "quarantine" than execution, unless the innovation was "extreme, persistent and aggressive". Another source, legal historian Sadakat Kadri, argues execution was rare because "it was widely believed" that any accused apostate "who repented by articulating the "shahada"" ("LA ILAHA ILLALLAH" "There is no God but Allah") "had to be forgiven" and their punishment delayed until after Judgement Day. This principle was upheld "even in extreme situations", such as when an offender adopted Islam "only for fear of death" and their sincerity seemed highly implausible. It was based on the hadith that Muhammad had upbraided a follower for killing a raider who had uttered the shahada.