Passage
His disciples say, Lo, now speakest thou plainly, and speakest no dark saying.
John 16:29 (ASV)
Nearby Context
John 16:27 for the Father himself loveth you, because ye have loved me, and have believed that I came forth from the Father.
John 16:28 I came out from the Father, and am come into the world: again, I leave the world, and go unto the Father.
John 16:29 His disciples say, Lo, now speakest thou plainly, and speakest no dark saying.
John 16:30 Now know we that thou knowest all things, and needest not that any man should ask thee: by this we believe that thou camest forth from God.
John 16:31 Jesus answered them, Do ye now believe?
Study Lenses
The verse centers on "disciples", "speakest", "thou", "plainly", "dark", and "saying". It is saying that the verse draws attention to "disciples" and "speakest", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 28's "I came out from the Father and..." into verse 30's "Now know we that thou knowest all...", so "disciples" and "speakest" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "disciples" and "speakest" with trust shaped by these words, not by a vague optimism outside the passage.