'Sign' in the Bible

And this to thee is the sign, Food of the year is the spontaneous growth, And in the second year the self-produced, And in the third year sow ye, and reap, And plant vineyards, and eat their fruits.

And Hezekiah saith unto Isaiah, 'What is the sign that Jehovah doth give healing to me, that I have gone up on the third day to the house of Jehovah?'

And Isaiah saith, 'This is to thee the sign from Jehovah, that Jehovah doth the thing that He hath spoken -- The shadow hath gone on ten degrees, or it doth turn back ten degrees?'

And he saith, 'What is this sign that I see?' and the men of the city say unto him, 'The grave of the man of God who hath come from Judah, and proclaimeth these things that thou hast done concerning the altar of Beth-El.'