Was Jesus command to watch in Matthew 26 just for that night or was it a general caution for the Church? Jesus charged his disciples to watch and pray in Matthew Chapter 26, and in earlier reading it seemed to me that he was probably referring to the events of that night.
In my more recent studies the statement in verse 41 &quot;That ye not enter into temptation&quot; caused me to wonder if he might not be giving a continuing instruction to watch for the temptations of Satan because he knew that after his death and resurrection, that Satan would then concentrate on the church.
Matthew 26:38 through 41  NRKJV

38  Then saith he unto them, My soul is exceeding sorrowful, even unto death: tarry ye here, and watch with me.
39  And he went a little further, and fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou wilt.
40  And he cometh unto the disciples, and findeth them asleep, and saith unto Peter, What, could ye not watch with me one hour?
41  Watch and pray, that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak.
In the context of this passage, I would consider it Risky Exegesis™ to apply it to people beyond who the speaker intended (based on what he says). In this case, he is speaking "to the disciples." I take that to mean meaning the three that went with him farther in: Peter, James and John. The text seems to indicate the objects of his speaking, and so redirecting the statement to new objects is the point at which I would be very cautious.

If you want a command from the Lord about prayer and temptation, the Lord's Prayer would probably suffice:


  Matthew 6:9-13 KJV  After this manner therefore pray ye: Our Father which art in heaven, Hallowed be thy name. Thy kingdom come . Thy will be done in earth, as it is in heaven. Give us this day our daily bread. And forgive us our debts, as we forgive our debtors. And lead us not into temptation, but deliver us from evil: For thine is the kingdom, and the power, and the glory, for ever. Amen.


This command has no limitations on audience or duration, and I read this section (the Sermon on the Mount) as applying to all Jesus' followers, henceforward throughout time.

An related question of interest might be, "How can I know if a Biblical mandate applies?" I see a number of people choose commands from the Bible (that they like, presumably) and say that those things apply to them, even though I cannot (personally) make build a logical case to support the idea.