"When a third of the night had passed, the Messenger of Allah ﷺ stood and said: 'O you people! Remember Allah! Remember Allah! The Rajifah is coming, followed by the Radifah, death and what it brings is coming, death and what it brings is coming!'" Ubayy said: "I said: 'O Messenger of Allah! Indeed I say very much Salat for you. How much of my Salat should I make for you?' He said: 'As you wish.'" [He said:] "I said: 'A fourth?' He said: 'As you wish. But if you add more it would be better for you.' I said: 'Then half?' He said: 'As you wish. And if you add more it would be better [for you].'" [He said:] "I said: 'Then two-thirds? 'He said: 'As you wish, but if you add more it would be better for you.' I said: 'Should I make all of my Salat for you?' He said: 'Then your problems would be solved and your sins would be forgiven.'" (Using translation from Tirmidhī 2457)
كَانَ رَسُولُ اللَّهِ ﷺ إِذَا ذَهَبَ رُبْعُ اللَّيْلِ قَامَ فَقَالَ «يَا أَيُّهَا النَّاسُ اذْكُرُوا اللَّهَ يَا أَيُّهَا النَّاسُ اذْكُرُوا اللَّهَ يَا أَيُّهَا النَّاسُ اذْكُرُوا اللَّهَ جَاءَتِ الرَّاجِفَةُ تَتْبَعُهَا الرَّادِفَةُ جَاءَ الْمَوْتُ بِمَا فِيهِ جَاءَ الْمَوْتُ بِمَا فِيهِ» فَقَالَ أُبَيُّ بْنُ كَعْبٍ يَا رَسُولَ اللَّهِ إِنِّي أُكْثِرُ الصَّلَاةَ عَلَيْكَ فَكَمْ أَجْعَلُ لَكَ مِنْهَا؟ قَالَ «مَا شِئْتَ» قَالَ الرُّبُعُ؟ قَالَ «مَا شِئْتَ وَإِنْ زِدْتَ فَهُوَ خَيْرٌ لَكَ» قَالَ النِّصْفُ؟ قَالَ «مَا شِئْتَ وَإِنْ زِدْتَ فَهُوَ خَيْرٌ لَكَ» قَالَ الثُّلُثَيْنِ؟ قَالَ «مَا شِئْتَ وَإِنْ زِدْتَ فَهُوَ خَيْرٌ» قَالَ يَا رَسُولَ اللَّهِ أَجْعَلُهَا كُلَّهَا لَكَ؟ قَالَ «إِذًا تُكْفَى هَمَّكَ وَيُغْفَرُ لَكَ ذَنْبُكَ»