Sunan an-Nasa'i, Volume 2, Book 11, Hadith 903 (DarusSalam) ⓘ
It was narrated from Anas that: The Prophet, Abu Bakr, and Umar, may Allah be pleased with them both, would start their recitation with: "All the praise and thanks be to Allah, the Lord of all that exists.
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم وَأَبُو بَكْرٍ وَعُمَرُ - رضى الله عنهما - يَسْتَفْتِحُونَ الْقِرَاءَةَ بِـ { الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ }
also referenced under: Hadith 902 (Reference) & Book 11, Hadith 27 (In-Book)