'Appear Before Me' in the Bible

You shall keep the feast of unleavened bread: (you shall eat unleavened bread seven days, as I commanded you, in the time appointed of the month Abib; for in it you came out from Egypt: and none shall appear before me empty:)

But the firstling of a donkey you shall redeem with a lamb: and if you redeem it not, then shall you break its neck. All the firstborn of your sons you shall redeem. And none shall appear before me empty.

When you come to appear before me, who has required this at your hand, to trample my courts?