What is the ruling on the prayer of one who intentionally says "Satan is greater" instead of "Allah is greater" in it?

Intentionally uttering something other than the opening takbir (Allahu Akbar) in its place, as a mockery of the prayer and the religion, constitutes an act of disbelief (kufr), as Allah Almighty says: "Say, 'Is it Allah and His verses and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief." Furthermore, the prayer is not valid without Al-Fatiha. The one who does this must repent and seek forgiveness, in accordance with the Almighty's saying: "Say to those who have disbelieved, if they cease, what has passed will be forgiven for them."