A.T. Robertson Commentary Matthew 14:22

"And straightway he constrained the disciples to enter into the boat, and to go before him unto the other side, till he should send the multitudes away." — Matthew 14:22 (ASV)

Constrained (ηναγκασεν). Literally, "compelled" or "forced." See this word also in Lu 14:23. The explanation for this strong word in Mr 6:45 and Mt 14:22 is given in Joh 6:15. It is the excited purpose of the crowd to take Jesus by force and to make him national king. This would be political revolution and would defeat all the plans of Jesus about his kingdom. Things have reached a climax. The disciples were evidently swept off their feet by the mob psychology for they still shared the Pharisaic hope of a political kingdom. With the disciples out of the way Jesus could handle the crowd more easily,

till he should send the multitudes away (εως ου απολυση τους οχλους). The use of the aorist subjunctive with εως or εως ου is a neat and common Greek idiom where the purpose is not yet realized. So in 18:30; 26:36. "While" sometimes renders it well. The subjunctive is retained after a past tense instead of the change to the optative of the ancient Attic. The optative is very rare anyhow, but Luke uses it with πριν η in Ac 25:16.