Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1249
Abu Huraira reported: I heard the Messenger of Allah (may peace be upon him) saying: When the Iqama has been pronounced for prayer, do not go running to it, but go walking in tranquillity and pray what you are in time for, and complete what you have missed.