(26) باب اسْتِحْبَابِ الذِّكْرِ بَعْدَ الصَّلاَةِ وَبَيَان صِفَتِهِ
Abu Zubair reported:
Abdullah b Zubair used to say La ilaha il-Allah at the end of every prayer like the hadith narrated by Ibn Numair and he reported it in the end, and then reported Ibn Zubair saying: The Messenger of Allah (ﷺ) uttered La ilaha il-Allah at the end of every prayer.
Reference: Sahih Muslim 594 b
In-book reference: Book 5, Hadith 181
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1236