Shaykh Salih al-Fawzan confirms that raising the voice in dhikr after prayer is a Sunnah. It was practiced by the Prophet ﷺ, his companions, and early generations. Ibn ʿAbbās noted that they could tell the prayer had ended by hearing the dhikr.
Is it from the sunnah to raise the voice in remembrance (dhikr) after the prayer or not?
Without a doubt, it is from the sunnah to raise the voice in remembrance (with dhikr) which has been narrated, words of remembrance have been narrated (to say) after the prayer. This is something which was present during the lifetime of the Prophet ﷺ and the lifetime of his companions. And the children and the youth, as Ibn ʿAbbās said: ‘We used to know that the prayer had ended by hearing the dhikr.’
