When Paul wrote to Timothy that _all_ Scripture was given by inspiration of God and was profitable, he meant what he said. "Well," some say, "do you believe all Scripture is given by inspiration?" Yes, every word of it; but I don't believe all the actions and incidents it tells of were inspired. For instance, when the devil told a lie he was not inspired to tell a lie, and when a wicked man like Ahab said anything, he was not inspired; but some one was inspired to write it, and so all was given by inspiration and is profitable.
Inspiration must have been verbal in many, if not in all, cases. Peter tells us, regarding salvation through the sufferings of Christ:
"Of which salvation the prophets have enquired and searched diligently, who prophesied of the grace that should come unto you. Searching what or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow. Unto whom it was revealed, that not unto themselves, but unto us they did minister the things, which are now reported unto you by them that have preached the gospel unto you with the Holy Ghost sent down from heaven; which things the angels desire to look into."
So that the prophets themselves had to enquire and search diligently regarding the words they uttered under the inspiration of the Spirit.
A man said to a young convert: "How can you prove that the Bible is inspired?" He replied, "Because it inspires me." I think that is pretty good proof. Let the Word of God into your soul, and it will inspire you, it can not help it.