It wasnarrated that Thawban said:
"I heard the Messenger of Allah(ﷺ)say: 'For every mistake there are two prostrations, after sayingthe Salam.'" (JA)
English reference (JA): Vol. 1, Book 5, Hadith 1219 (JA)
Arabic reference (JA): Book 5, Hadith 1276 (JA)