Donald Trump raised his right hand while placing his left hand on the Bible Monday afternoon. He then took the oath of office and was sworn in as the 47th President of the United States.

President Donald Trump faced backlash after critics noted that he did not place his hand on the Bible during his inauguration on Monday, raising questions about the tradition’s significance during the formal ceremony.

The tradition of swearing the oath of office on a Bible stretches back to George Washington, but not all presidents have observed it.