I heard the Messenger of Allah ﷺ say: When the iqamah is pronounced for prayer, do not come to it running, but come walking(slowly). You should observe tranquility. The part of the prayer you get(along with the imam) offer it, and the part you miss complete it (afterward).  

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ إِذَا أُقِيمَتِ الصَّلاَةُ فَلاَ تَأْتُوهَا تَسْعَوْنَ وَأْتُوهَا تَمْشُونَ وَعَلَيْكُمُ السَّكِينَةُ فَمَا أَدْرَكْتُمْ فَصَلُّوا وَمَا فَاتَكُمْ فَأَتِمُّوا  

Come to prayer with calmness and tranquility. Then pray the part you get (long with the imam) and complete afterwards the part you miss. Abu Dawud said: Ibn Sirin narrated from Abu Hurairah the words: "he should complete it afterwards." Similarly, Abu Rafi' narrated from Abu Hurairah and Abu Dharr narrated from him the words "then complete it, and complete it afterwards." There is a variation of words in the narration from him.  

عَنِ النَّبِيِّ ﷺ قَالَ ائْتُوا الصَّلاَةَ وَعَلَيْكُمُ السَّكِينَةُ فَصَلُّوا مَا أَدْرَكْتُمْ وَاقْضُوا مَا سَبَقَكُمْ