Mukhtasar Bukhari

Narrated from Sayyiduna Abu Bakr (may Allah be pleased with him) that he reached the Prophet (peace and blessings of Allah be upon him) while he was in the state of bowing (ruku‘), so before joining the row, he performed ruku‘. He mentioned this to the Prophet (peace and blessings of Allah be upon him), so he (peace and blessings of Allah be upon him) said: "May Allah increase your eagerness (for good deeds), but do not do this again."