Sunan an-Nasa'i #965 · The Book of the Commencement of the Prayer

Sunan an-Nasa'iIt was narrated that Abu Hurairah said
Sunan an-Nasa'i · Book 11 · The Book of the Commencement of the Prayer
Sunan an-Nasa'i · كتاب 11 · كتاب افتتاح الصلاة
"Abu Bakr and Umar prostrated during: 'When the heaven is split asunder,' as did the one who was better than them (the Prophet (ﷺ)
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا قُرَّةُ بْنُ خَالِدٍ، عَنْ مُحَمَّدِ بْنِ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ سَجَدَ أَبُو بَكْرٍ وَعُمَرُ - رضى الله
عنهما - فِي ‏{‏ إِذَا السَّمَاءُ انْشَقَّتْ ‏}‏ وَمَنْ هُوَ خَيْرٌ مِنْهُمَا ‏.‏
Reference : Sunan an-Nasa'i 965In-book reference : Book 11, Hadith 90