Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates: The people's raising their voices in dhikr (remembrance of Allah) after finishing the obligatory prayer (was the practice). He was asked: "Did the Prophet (peace and blessings be upon him) do so?" Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "I would know of it only when I heard it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12160