# write in sealed scrolls. They will assemble witnesses

These are the deeds that a person would sign to purchase land. Other people would be the witnesses.

# reverse their captivity

"free them from those who had captured them". See Jeremiah 29:14.

# this is Yahweh's declaration

"this is what I, Yahweh, have declared". Yahweh speaks of himself to express the certainty of what he is declaring. See Jeremiah 1:8.