Imām Sa’īd b. Al-Musayyib – Allāh have mercy on him – once saw a man praying more than two rak’ah after sunrise the beginning of Fajr, making many bows and prostrations, and so he forbade him. The man said, “O Abu Muḥammad, is Allāh going to punish me for praying?” Sa’īd said, “No, but He will punish you for contradicting the Sunnah.”

Al-Bayhaqī, As-Sunan Al-Kubraa 2:466. graded ṣaḥīḥ by Shaykh Al-Albānī. See Irwā Al-Ghalīl 2:236.

Shaykh Al-Albānī writes:

This is one of the superb answers given by Sa’īd b. Al-Musayyib – Allāh have mercy on him. It is a strong weapon against heretics (mubtadi’ah) who recommend many different types of religious innovation in the name of them being dhikr and prayer. They then criticize the followers of the Sunnah for criticizing them, and accuse them of censuring dhikr and prayer, when in fact [Ahl Al-Sunnah] are only criticizing the contravention of the Sunnah in matters such as dhikr and prayer.