Excerpt from The Life of St. Antony:

Wherefore if they pretend to foretell the future, let no one give heed, for often they announce beforehand that the brethren are coming days after. And they do come. The demons, however, do this not from any care for the hearers, but to gain their trust, and that then at length, having got them in their power, they may destroy them. Whence we must give no heed to them, but ought rather to confute them when speaking, since we do not need them. For what wonder is it, if with more subtle bodies than men haves, when they have seen them start on their journey, they surpass them in speed, and announce their coming? Just as a horseman getting a start of a man on foot announces the arrival of the latter beforehand, so in this there is no need for us to wonder at them. For they know none of those things which are not yet in existence; but God only is He who knoweth all things before their birth. But these, like thieves, running off first with what they see, proclaim it: to how many already have they announced our business--that we are assembled together, and discuss measures against them, before any one of us could go and tell these things. This in good truth a fleet-footed boy could do, getting far ahead of one less swift. But what I mean is this. If any one begins to walk from the Thebaid, or from any other district, before he begins to walk, they do not know whether he will walk. But when they have seen him walking they run on, and before he comes up report his approach. And so it falls out that after a few days the travellers arrive. But often the walkers turn back, and the demons prove false.