I don't know why he chose that particular expression. Maybe he thought the slave theme was overused, and was looking for some other way to humble himself before the Lord...
In any case, this guy was close, but he only made it half way. Got himself half the expression - the "down" part, forgetting all about the "face". The resulting word, "Artza", literally means "to the ground" and is commonly used to tell a dog to lie down. You know, the Hebrew version of "Down, boy!"
Now if you wanted an actual "Facedown" in Hebrew, it would be "Apaim Artza", which you would write like this:
