Musnad Ahmad 30:112

'Abd al-Rahman narrated to us, from Malik, from al-'Ala' ibn 'Abd al-Rahman, from his father, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him), who said: "Do not come to the prayer while you are rushing. Come to it while you are upon tranquility. Whatever you catch, pray it, and whatever you miss, complete it."