'Happen' in the Bible

They were on the road going up to Jerusalem, and Jesus was walking on ahead of them; and they were amazed, and those who followed were fearful. And again He took the twelve aside and began to tell them what was going to happen to Him,

Truly I say to you, whoever says to this mountain, ‘Be taken up and cast into the sea,’ and does not doubt in his heart, but believes that what he says is going to happen, it will be granted him.

But pray that it may not happen in the winter.