Is it prescribed to recite the adhkar after the voluntary prayer?

Question:
This questioner asks: Are the prescribed adhkar after the voluntary prayer a religious innovation (bid'ah)?

Answer:
The adhkar were only reported to be recited after the obligatory prayer: the takbirat of ten, or the tasbih, takbir, and tahmid thirty-three times each, completing one hundred, and "La ilaha illa Allah." This was reported after the obligatory prayer and is not said after the voluntary prayer. After the voluntary prayer, one seeks forgiveness and makes supplication. As for the adhkar that were reported after the obligatory prayer, they are not to be made after the voluntary prayer.