table - a tablet (Hab 2:2), which should be set in public, containing the prophecy in a briefer form, to be read by all.
a book - namely, a parchment roll, containing the prophecy in full, for the use of distant posterity. Its truth will be seen hereafter when the event has come to pass. See on Isa 8:1; Isa 8:16.
for ever and ever - rather read, “For a testimony for ever” [Chaldee, Jerome, Lowth]: “testimony is often joined to the notion of perpetuity (Deu 31:19, Deu 31:21, Deu 31:26).