What was this "cup" that Jesus asked might pass from Him if it were His Father's will? Was He, in a moment of weakness, asking His Father to prevent Him from going through the coming hours of physical torture? This is doubtful considering that Jesus, with the fullest knowledge and foresight of all the horrible details, had spent His entire human lifetime, and millennia prior to it, in preparation for this day.
A brief word study on these verses may prove helpful here. The word "cup" is translated from the Greek noun poterion, which can mean the vessel's liquid contents as well as the vessel itself. It is obvious, of course, that Jesus drank the contents, not the vessel. Poterion derives from pino, "to drink."
The word "pass" is translated from the Greek verb parerchomai, which can refer to the passage of time. From this, we can deduce that Jesus may have been asking His Father to make the time it would take to complete this awful "drink" pass as quickly as possible, but even then, only if it fit in with His Father's perfect will.
Most of us have at some time had to drink some horrible-tasting medicine, and although we knew that it was beneficial for us to drink it, the procedure still seemed to take an eternity! By prior agreement with His Father, Jesus was at this time voluntarily draining an enormous cup of spiritual "drink," which was ultimately a healing medicine for mankind but at the same time was to Him a deadly poison.
This spiritual drink was a mixture of two ingredients that could not have been more repulsive to Them both. The first ingredient was the sin of the whole world. The second was Their separation from each other. Jesus' spiritual poison did not just taste horrible. It racked His body and His mind with stinging agony (I Corinthians 15:56; Luke 22:44). Perhaps, in agreeing to drink of this cup, He even accepted a taste of the fiery fate of those who would never repent, as foretold through the prophet Jeremiah that the poison was like fire that had been injected into His bones (Lamentations 1:13).