In Matthew 26:40-46; how many hours did Jesus pray in the Garden of
Gethsemane? only one or three?

I had a hard time imagining why it would be important to know
how long he prayed in the garden. Normally when such a question is asked,
there is some underlying issue behind the question, such as a criticism of
the Bible leveled by a skeptic. In this case, I do not know of a reason
this is a key question.

Nevertheless, I will answer to the best of my ability. After
going away from Peter, James and John for the first time in the garden to
pray, Jesus came back and with anguish and disappointment asked, “Could
you men not keep watch with me for one hour?” From this, we can deduce
that probably the first session of prayer lasted somewhere around one
hour. If anything, it might have been less than one hour, as Jesus
specifically said they could not even last an hour. Because a more exact
amount of time is not given, we should simply say somewhere around an hour
for the first session of prayer. Bear in mind that people back at that
time did not have watches, and generally kept mental track of time with
far less precision than we do. No one back then would ever have said,
“wait for me for 55 minutes, then do such and such.” If, in the Bible,
one reads an event took two hours, this should be taken to mean probably
more than one hour and probably less than three hours.

After the first prayer session, Jesus returned to pray two
more times. In both cases, the length of prayer was sufficient for the
disciples to fall asleep, despite having been admonished and asked to stay
awake. It would not be unreasonable to think that these two sessions also
lasted an hour or so, but bottom line we simply do not know. Like I
already said, I am not sure why it would be important to estimate the
length of time Jesus prayed, but if I were asked to give an estimate, I
would estimate that Jesus prayed about three hours, but to be honest, I
simply do not know how long he prayed. We do know that he finished
praying while it was still dark and that he started somewhat late at
night, but beyond that, we simply do not know.

John Oakes