A minor objection of some critics asks how it is that the authors of the Gospels could possibly have known the content of what Jesus prayed in the Garden of Gethsemane. Presumably, Jesus was far away enough from Peter, James, and John that he did not know they were asleep until he came back to find them sleeping. The charge is then made that Mark simply made up the prayer of Jesus for our edification.
The main question to ask is, how far, exactly, was Jesus from his three disciples? Matthew and Mark say only "a little farther" (Mark 14:35; Matt. 26:39). Both use the word mikron to describe the distance -- and I think that word, even in Greek, speaks for itself. Matthew and Mark see no great distance here.
What then of Luke? He places Jesus "about a stone's throw beyond them" (Luke 22:41). How far is this? Only Fitzmeyer's Lukan commentary makes any guess [1441]; he says it is not out of sight, but out of hearing range. How Fitzmeyer deduces this is not explained. He refers to a parallel phrase in Thucydides, "as far as a stone's or a javelin's throw." Presumably a soldier could throw farther than the average person; but isn't there another matter of how loudly the other person is talking as well? Luke 22:44 ["And being in an agony he prayed more earnestly"], albeit questionable in terms of textual criticism, would seem to indicate that Jesus' prayer might have been quite loud.
Either way, what is the distance? We simply don't know. Therefore, that the disciples are recorded as having indeed heard what Jesus said should interpret what the distance is.
Contrary to the critics, I see no implication that Jesus went beyond hearing distance. Nor do any of the Gospels report hearing and observation of anything that the disciples could not have seen and heard before falling asleep. The "one hour" comment certainly allows for a lot of room for listening/watching disciples, and it is unreasonable to assume that in the first moment of that hour after the command of Jesus the disciples went straight to sleep. They would have struggled to stay awake--but would have eventually fallen asleep due to sadness; and in each of the three incidences of prayer, there would have been period of alertness/attention prior to be yet again overcome with fatigue, allowing time for observation and overhearing.
Finally, there is hardly any indication that Jesus could not tell the disciples were asleep; what is recorded is only his admonishment to them, in the form of a question -- it no more indicates ignorance of their turpitude than the proverbial mother asking her child if he was the one that broke the cookie jar.
And indeed, if Mark is being the "know it all narrator" here, why didn't he invent something more useful for apologetics purposes, like a long speech by Jesus against His would-be tormentors? Why make Jesus look so "weak"? The fact that we are not given an extended account of Jesus' prayers in the Garden is in and of itself an indication that we have been given a valid, eyewitness account of what the disciples did see and hear that painful night.
-JPH