++ [ originally posted by Rami] ++
This is the full Paragraph from wikipedia:
A hadith of questionable authenticity[1], related by Ibn Asakir in Târîkh Dimashq and attributed by its narrator Salmân b. `Abd Allah to Islam's prophet Muhammad, expresses a common sentiment in declaring that:
"Being an Arab is not because of your father or mother, but being an Arab is on account of your tongue. Whoever learns Arabic is an Arab."
From Islamtoday:
This hadîth is related by Ibn`Asâkir in Târîkh Dimashq. It is a very weak hadîth. Ibn `Asâkir, al-Dhahabî and al-Nasâ’î declared its narrator, Salmân b. `Abd Allah to be extremely weak and unreliable.