George Washington is believed to have appended "so help me God" to the oath when he was sworn in. Whether it was Washington, or someone later, it's mere tradition, and strictly not very Quaker. The Quakers insisted on the option to affirm, rather than swear, the oath. I also added "binding" to the original language. Charles III of England was convicted in court of not honoring his oath, and executed, which initiated a period where England was a commonwealth rather than a monarchy. That's what binding means. That's what oath means. But I'll leave all that here in the notes.
I also stick Washington in here by name to atone for, and hopefully diminish the shock of, suggesting that my own name be part of the text of the US Constitution. That's a bit much, even for me, but we are in crucial times, and expedients must be taken.