Musnad Ahmad 830:63

'Abd al-Samad narrated to us, Bashshar al-Khayyat narrated to us, he said: I heard 'Abd al-'Aziz ibn Abi Bakrah narrating that Abu Bakrah came while the Prophet, peace and blessings of Allah be upon him, was bowing. The Prophet, peace and blessings of Allah be upon him, heard the sound of Abu Bakrah's sandals while he was hurrying, wanting to catch the rak'ah. When the Prophet, peace and blessings of Allah be upon him, finished, he said: "Who is the one who was hurrying?" Abu Bakrah said: "I am." He said: "May Allah increase you in eagerness, but do not do it again."