It is narrated by Bukhari and Muslim and mentioned by Jalaluddin
as-Suyuti, from other collections, that 'Ali bin Abi Talib (r) said, "I
asked the Prophet (s) one time, 'O Messenger of Allah, guide me to the
shortest way to Allah's Presence, and the easiest way to worship, and
the best way for Allah, Almighty and Exalted. The Prophet (s) said, 'O
'Ali, you have to be continuously making Dhikrullah, silently and
aloud.' I replied, 'O Prophet (s), all human beings are making dhikr.
Give me something special.' The Prophet (s) said, 'O 'Ali, the best of
what I, and all prophets before me, said is, la ilaha illallah. If all the heavens and earth were placed on one side of the balance and la ilaha illallah were placed in the other, la ilaha illallah would be heavier. Judgment Day will never come as long as there are people on this earth saying la ilaha illallah.' Then I said, 'How should I recite.' The Prophet (s) said, 'Close your eyes and listen to me reciting la ilaha ill-Allah three
times. Then you say it three times and I will listen to you.' Then the
Prophet (s) said it and I repeated it in a loud voice."
In the narration of Imam Ahmad and Tabarani this hadith is continued,
describing how the Prophet taught his Companions the dhikr. "'Ibada bin
Samit said that the Prophet (s) said, 'Is there any stranger among you?'
And we said, 'No, Ya Rasul-Allah.' He said, 'Close the door.' Then he
said, 'Raise your hand and repeat after me La ilaha illallah' We raised our hand and said, la ilaha illallah.
Then the Prophet (s) said, 'Praise be to Allah that He sent me to this
world with this kalimah, and He ordered me with it, and He promised me
the Paradise with it, and He never changes His Promise.' Then the
Prophet (s) said, 'Be happy! Allah has forgiven you.'"
