[Machine] Indeed, the Prophet, peace be upon him, used to say "Subhanal-Malikil-Qudoos" three times in a raised voice after saying the Salam. It has been narrated by Abdur-Rahman ibn Abza, who is one of those considered reliable by us, that he never met the Prophet, peace be upon him, except that his most frequent report was from Ubay ibn Ka'b and the Companions. This chain of narrators is authentic according to the conditions of Al-Bukhari and Muslim, and they did not exclude it, and the Hadith is authentic.  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا سَلَّمَ قَالَ «سُبْحَانَ الْمَلِكِ الْقُدُّوسِ» ثَلَاثًا يَرْفَعُ صَوْتَهُ «عَبْدُ الرَّحْمَنِ بْنُ أَبْزَى مِمَّنْ صَحَّ عِنْدَنَا أَنَّهُ أَدْرَكَ النَّبِيَّ ﷺ إِلَّا أَنَّ أَكْثَرَ رِوَايَتِهِ عَنْ أُبَيِّ بْنِ كَعْبٍ وَالصَّحَابَةِ» وَهَذَا الْإِسْنَادُ صَحِيحٌ عَلَى شَرْطِ الشَّيْخَيْنِ وَلَمْ يُخَرِّجَاهُ والحديث صحيح