According to Goitein, the inscriptions decorating the interior clearly display a spirit of polemic against Christianity, whilst stressing at the same time the Qur'anic doctrine that Jesus was a true prophet. The formula "la sharika lahu" ("God has no companion") is repeated five times; the verses from Sura Maryam 19:35–37, which strongly reaffirm Jesus' prophethood to God, are quoted together with the prayer: "Allahumma salli ala rasulika wa'abdika 'Isa bin Maryam" – "O Lord, send your blessings to your Prophet and Servant Jesus son of Mary." He believes that this shows that rivalry with Christendom, together with the spirit of Muslim mission to the Christians, was at work at the time of construction.