We used to sit in front of Abdullah ibn Masoud’s (r.a) house before the Fajr prayer waiting to go with him to the Masjid. Abou Mousa al-Ash`aarie (r.a) came and asked us: ‘Did Abu Abdurrahman (i.e. Ibn Masoud) leave yet?’
We answered: ‘No.’
So Abou Mousa Al-Ashaari (r.a) sat with us waiting for him. When he came out, we all stood up. Abou Mousa Al Ashaari (r.a) told him:
“Oh, Abu Abdurrahman (i.e Abdullah ibn Masood) ! I recently saw something in the Masjid which I did not approve.”
Ibn Masoud then asked: “What was it?”
Abou Mousa said: “You will see it if you stay alive..In the Masjid, I saw a group of people sitting in circles waiting for the Salat. Each circle is led by a person. And every person in these circles carries small stones.
The leader of a circle would say: ‘Say ‘Allah-u Akbar’ a hundred times,’ they will say Allah-u Akbar a hundred times; then he says ‘Say ‘La ilaha Illa Allah’, a hundred times” they will say La ilaha ill Allah a hundred times; he they says: ‘Say ‘Subhan Allah’, a hundred times, they will say Subhana Allah a hundred times.
Then Ibn Masoud said: “What did you tell them?”
He (Abu mousa al ashaari) said: ‘I didn’t say anything, I wanted to wait for your opinion.”
Abdullah ibn Masoud (angrily) said: “Could you not order them to count their sins, and assured them of getting their rewards.”Then Abdulah ibn Masoud went ahead and we accompanied him. As he approached one of the circles, he said: “What is this that you are doing?”
They said: “Oh! Abu Abdurrahman, these are pebbles to count the number of times we say Allah-u Akbar, La ilaha Ill Allah, and Subhana Allah.”
He said: “Count your own sins, and I assure you that you are not going to lose anything of your rewards (Hasanat).. Woe unto you, people of Muhammad, how fast you will be doomed. Those are your Prophet’s companions available, these are his clothes not worn out yet, and his pots are not broken yet. I swear by Whom my soul is in His Hands that you are either following a religion that is better than the Prophet’s religion or you are opening a door of aberration.”
They said: “We swear by Allah, oh, Abu Abdurrahman, that we had no intention other than doing good deeds.”
He said: “So what? How many people wanted to do good deeds but never got to do them? The Prophet of Allah has told us about people who recited the Qur’an with no effect on them other than the Qur’an passing through their throats. I swear by Allah, I am almost sure that most of you are from that type of people.”
Then he (Ibn Masood) left them.
Amr Ibn Salamah said: “We saw most of the people of those circles fighting us with the Khawarij in the battle of An-Nahrawan.”
i.e All those people who wanted to do good deeds by innovating a practise in Islam, were fighting against the sahabas in the battle of nahrawan i.e. they were in the gangs/army of the khawarijites (accursed)