"Abu Bakr and Umar prostrated during: 'When the heaven is split asunder,' as did the one who was better than them (the Prophet ﷺ). " (Using translation from Nasāʾī 965)
«سَجَدَ أَبُو بَكْرٍ وَعُمَرُ فِي إِذَا السَّمَاءُ انْشَقَّتْ وَمَنْ هُوَ خَيْرٌ مِنْهُمَا ﷺ»