'Appear Before Me' in the Bible

Thou shall keep the feast of unleavened bread (Seven days thou shall eat unleavened bread, as I commanded thee, at the time appointed in the month Abib, for in it thou came out from Egypt, and none shall appear before me empty),

And the firstling of a donkey thou shall redeem with a lamb, and if thou will not redeem it, then thou shall break its neck. All the first-born of thy sons thou shall redeem. And none shall appear before me empty.

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