Robert of Ketton receives support from the Church—he becomes Archdeacon of Pamplona in 1143—but his preference is for translating scientific rather than theological works.

He is known to have studied Euclid and to have translated the work of Al Battani and Avicenna, and it seems that he would not have made the translation for which he is famous, that of the Qur'an, without the encouragement of the French Abbot Peter the Venerable, who wished to have access to Islamic texts.

Robert and other scholars had met in 1142 with Peter the Venerable, who was visiting Spain, and Robert set to work translating the Qur'an into Latin.

The translation is done by 1143; entitled Lex Mahumet pseudoprophete, it is the first translation of the book into a European language and will remain the standard well into the sixteenth century.

The translation is not viewed by modern scholars as having been faithful, but rather includes some passages with distortions or exaggerations of the original Arabic.