Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1250
Abu Huraira reported that the Messenger of Allah (may peace be upon him) said: When the words of Iqama are pronounced, do not come to (prayer) running, but go with tranquillity, and pray what you are in time for, and complete (what you have missed) for when one of you is preparing for prayer he is in fact engaged in prayer.