Meursault thinks" that in the long run one gets used to anything." Who orignally said this to him?

Meursault's mother.

Explanation:

Albert Camus's "The Stranger" revolves around the character of Meursault who, due to his unusual reaction to the death of his mother led to some unfortunate events. The novel deals with the theme of how man is an alien, a stranger, a foreigner if he refuses any help and becomes isolated mentally, physically, and emotionally.

The phrase "in the long run, one gets used to anything" was frequently used by his now-dead mother. Meursault remembers this quote whenever he began thinking of what his life means and what will happen and how fortunate he is, even though in prison. For, life could well be far worse than being a prisoner.