'Sign' in the Bible

Make a request, and it will be answered; what you are searching for you will get; give the sign, and the door will be open to you:

Because to everyone who makes a request, it will be given; and he who is searching will get his desire, and to him who gives the sign, the door will be open.

Then some of the scribes and Pharisees, hearing this, said to him, Master, we are looking for a sign from you.

But he, answering, said to them, An evil and false generation is looking for a sign; and no sign will be given to it but the sign of the prophet Jonah:

And the Pharisees and Sadducees came and, testing him, made a request to him to give them a sign from heaven.

An evil and false generation is searching after a sign; and no sign will be given to it but the sign of Jonah. And he went away from them.

And while he was seated on the Mountain of Olives, the disciples came to him privately, saying, Make clear to us, when will these things be? and what will be the sign of your coming and of the end of the world?

And then the sign of the Son of man will be seen in heaven: and then all the nations of the earth will have sorrow, and they will see the Son of man coming on the clouds of heaven with power and great glory.

Now the false one had given them a sign saying, The one to whom I give a kiss, that is he: take him.