Imam Sa’id ibn al-Musayyib {May Allah have mercy upon him} once saw a man praying more than two rak’ah after the beginning of Fajr, he was making many bows and prostrations, and so he forbade him from doing that.
The man {May Allah have mercy upon him} said,
“O Abu Muhammad, is Allah going to punish me for praying?” Imam Sa’id ibn al-Musayyib said, “No, but He will punish you for contradicting the Sunnah.”
(Related by al-Bayhaqi, As-Sunan Al-Kubra Volume 2 pg. 466)