'Abdullah ibn 'Amr reported that the Prophet, may Allah blesshim and grant him peace, said, "If a Muslim man persists in two actions,he will enter the Garden. They are easy, but those who do them are few.'He was asked, 'What are they, may Allah bless him and grant him peace?'He said, 'That you say "Allahu akbar" ten times, "al-hamdu lillah"ten times, and "Subhana'llah" ten times after every prayer.That is 150 on the tongue and 1500 in the balance.' I saw the Prophet,may Allah bless him and grant him peace, counting them with his hand. Thenhe said, 'When you go to bed, you should say, "Subhana'llah", "al-hamdulillah", and "Allahu akbar". That is 100 on the tongue and 1000in the balance. Who among you can do 2500 bad actions morning and night?'He was asked, 'Messenger of Allah, how is it that they are not counted?'He said, 'Shaytan comes to one of you while he is praying and reminds himof something he has to do such-and-such and such-and-such, so he does notremember to do it.'"
English reference: Book 50, Hadith 1216
Arabic reference: Book 1, Hadith 1216