Fatima came to the Prophet ﷺ asking for a servant. He said, "May I inform you of something better than that? When you go to bed, recite "Subhan Allah' thirty three times, 'Al hamduli l-lah' thirty three times, and 'Allahu Akbar' thirty four times. ʿAli added, 'I have never failed to recite it ever since." Somebody asked, "Even on the night of the battle of Siffin?" He said, "Even on the night of the battle of Siffin."
أَنَّ فَاطِمَةَ عَلَيْهَا السَّلاَمُ أَتَتِ النَّبِيَّ ﷺ تَسْأَلُهُ خَادِمًا فَقَالَ أَلاَ أُخْبِرُكِ مَا هُوَ خَيْرٌ لَكِ مِنْهُ تُسَبِّحِينَ اللَّهَ عِنْدَ مَنَامِكِ ثَلاَثًا وَثَلاَثِينَ وَتَحْمَدِينَ اللَّهَ ثَلاَثًا وَثَلاَثِينَ وَتُكَبِّرِينَ اللَّهَ أَرْبَعًا وَثَلاَثِينَ ثُمَّ قَالَ سُفْيَانُ إِحْدَاهُنَّ أَرْبَعٌ وَثَلاَثُونَ فَمَا تَرَكْتُهَا بَعْدُ قِيلَ وَلاَ لَيْلَةَ صِفِّينَ قَالَ وَلاَ لَيْلَةَ صِفِّينَ