'It is obligatory upon every muslim to learn the Arabic tongue to the utmost of his ability in order to be able to profess through it that - there is none worthy of worship other than Allah, and Muhammad is His servant and Messenger - and to recite in the Arabic tongue the Book of Allah, and to speak in mentioning what is incumbent him - the takbir of salah and what other matters are commanded, the tasbih, the tashahhud and others.' (Imam Shafi'i - in: 'ar-Risalah')
