“Friendship is not a game to play, It is not a word to say, It doesn't start on March and ends on May, It is tomorrow, yesterday, today and everyday.”

"Tomorrow" (1919), as translated in A Soviet Heretic : Essays by Yevgeny Zamyatin (1970) edited and translated by Mirra Ginsburg
Context: Yesterday, there was a tsar, and there were slaves; today there is no tsar, but the slaves remain; tomorrow there will be only tsars. We march in the name of tomorrow's free man — the royal man. We have lived through the epoch of suppression of the masses; we are living in an epoch of suppression of the individual in the name of the masses; tomorrow will bring the liberation of the individual — in the name of man. Wars, imperialist and civil, have turned man into material for warfare, into a number, a cipher. Man is forgotten, for the sake of the sabbath. We want to recall something else to mind: that the sabbath is for man.
The only weapon worthy of man — of tomorrows's man — is the word.

Introduction, The Nature of Probability Theory, p. 6.
An Introduction To Probability Theory And Its Applications (Third Edition)

Estoy en el ayer, en el hoy. ¿Y en mañana? En el mañana estuve.
Voces (1943)

Source: The Time Keeper

Letters to World Citizens (2004)

Source: The Lost Thing

Source: War and Peace

Source: The Sisterhood of the Traveling Pants