وَ كَانَ رَسُولُ اللَّهِ ص أَتَمَّ النَّاسِ صَلَاةً وَ أَوْجَزَهُمْ كَانَ إِذَا دَخَلَ فِي صَلَاةٍ قَالَ اللَّهُ أَكْبَرُ بِسْمِ اللَّهِ الرَّحْمنِ الرَّحِيمِ.
English translationBab Ul Qaim Publications
Hadith.920 - "The Messenger of Allah (sw) was the most complete in performing prayer and the most concise. When he began his prayer, he would say: 'Allāhu Akbar (God is the Greatest)' and then recite, 'Bismillāh al-Raḥmān al-Raḥīm (In the name of Allah (swt), the Most Gracious, the Most Merciful).'"
Translation: Bab Ul Qaim Publications·Thaqalayn link·The Arabic above is the original.