From Sahih Muslim (Hadith 1281):
Abdullah (b. Mas'ud) reported:The Apostle of Allah (ﷺ) said five rak'ahs of the noon prayer and when he completed the prayer, It was said to him: Has there been (commanded) an addition In prayer? He said: What is it? They said: You have said five rak'ahs, so he performed two prostrations
Reference: Muslim 1281