There is a surviving coin minted for the 8th century King Offa of Mercia (in what is now central England) with the Shahadah on it in badly-spelled Arabic, even

There is a surviving coin minted for the 8th century King Offa of Mercia (in what is now central England) with the Shahadah on it in badly-spelled Arabic, even though Mercia had been Christian for over a century when the coin was minted. https://www.bl.uk/collection-items/gold-dinar-of-king-offa# https://www.bl.uk/collection-items/gold-dinar-of-king-offa# (The coin is a copy of an Abbasid dinar from 773-4 CE, with "OFFA REX" added to it. It's the oldest known gold coin from post-Roman Britain.)