Isa 8:16 is considered a key reference regarding the formation of the book of Isaiah and the role of prophetic disciples in this process. This article argues, however, that originally this verse had a more limited significance. The instruction to which v. 16 refers is to be identified with vv. 12-15 rather than an early ‘book’ of Isaiah. The expression ‘the instructed ones’ (of YHWH rather than the prophet) is applied to the prophet’s audience.