Exodus 16:32

And Moses said, This is the thing which the Lord commandeth, Fill an omer of it to be kept for your generations; that they may see the bread wherewith I have fed you in the wilderness, when I brought you forth from the land of Egypt.

Cross-reference

Exodus 16:36 defines an omer as a tenth of an ephah, clarifying the measure used in the memorial command.

Psalm 105:5 commands remembering God's wondrous works; the omer of manna is a concrete reminder of that miracle.

Psalm 111:4 says God causes his works to be remembered; the manna memorial fulfills that purpose.

Luke 22:19 institutes a memorial of Jesus' body using bread; the manna memorial prefigures this, as Jesus is the bread of life.

Numbers 17:10 commands keeping Aaron's staff as a sign; similar to the manna memorial, both are physical reminders.