Often attributed to Stalin, there is not a single source which show that Stalin said this at any given time. There is only one source outside the blogosphere which attributes the quote to Stalin, but does not provide any evidence for the attribution. That source is the book Quotations for Public Speakers : A Historical, Literary, and Political Anthology (2001), p. 121 by the former US senator Robert Torricelli.
Misattributed
Joseph Stalin: Power
Joseph Stalin was General secretary of the Communist Party of the Soviet Union. Explore interesting quotes on power.
Stalin's article "Our purposes" Pravda #1, (22 January 1912)
Stalin's speeches, writings and authorised interviews
Source: The Foundations of Leninism, Ch.8
“The press must grow day in and day out — it is our Party's sharpest and most powerful weapon.”
Speech at The Twelfth Congress of the R.C.P.(B.) (19 April 1923) http://marx2mao.com/Stalin/TC23.html#s2
Stalin's speeches, writings and authorised interviews
But this contradiction is a living thing and wholly reflects the Marxist dialectic.
Address to the 16th Congress of the Russian Communist Party (1930) Quoted in: Alfred B. Evans, Soviet Marxism-Leninism: The Decline of an Ideology pg. 39 https://books.google.com/books?id=ezGGPIze4ZYC&pg=PA39&dq=withering+away+of+the+state+stalin&hl=en&sa=X&ved=0CCAQ6AEwAWoVChMIz_WZ46adxwIVR5YeCh1g7AKD#v=onepage&q=withering%20away%20of%20the%20state%20stalin&f=false
Stalin's speeches, writings and authorised interviews
You see, even when Herr Hitler wants to speak of peace he cannot avoid uttering threats. This is symptomatic.
https://www.marxists.org/reference/archive/stalin/works/1936/03/01.htmInterview Between J. Stalin and Roy Howard; March 1, 1936
Stalin's speeches, writings and authorised interviews
Problems of Leninism, August 1924 edition
The Foundations of Leninism
Source: The Problems of Leninism, Ch.8