From Was Jesus an Open Theist:
1. Jesus rebuked his disciples for evidently not believing that the future was flexible and not fixed, or that it could be altered. “Thinkest thou that I cannot now pray to my Father, and he shall presently give me more than twelve legions of angels?” Matt. 26:53. Here we see Jesus teaching open theism and essentially rebuking his disciples for not believing in open theism. Jesus was saying that he had a free will choice between alternative possibilities.
2. “And pray ye that your flight be not in the winter.” Mark 13:18. Here Jesus taught the open theists view of prayer, that prayer can literally affect, determine, and change the future. If there were no alternative future possibilities that were as of yet undecided, prayer for the future would be useless and vain. If all future events were already an eternal fixity, praying for certain events in the future to happen or not happen or to happen a certain way would not matter one iota.
3. “And except those days should be shortened, there should no flesh be saved: but for the elect’s sake those days shall be shortened.” Matt. 24:22. Here Jesus taught not only that God has the sovereign ability to change the future (aka open theism) but that God has in fact, in this particular, changed the future. The Bible, in both Testaments, teaches God’s ability to lengthen or shorten a man’s days. Thus, the future is flexible and changeable, not eternally fixed and concrete.