Hawzah News Agency – Imam al-Sadiq (pbuh), when asked about [devilish] misgivings, and if they happen often, said:
لا شيءَ فيها، تقولُ: لاإلهَ إلّا اللَّهُ.
'They are insignificant. Just say: 'There is no God but Allah (la ilaha illa Allah).'
Source: al-Kafi, v. 2, p. 424, no. 1