question #3 Sahih Muslim 602b, Book 5, Hadith 195 : What does it mean to be engaged in prayer while preparing for it?

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.