There's an instance in the Bible where King Hezekiah was ill (he had a boil on his body which was serious enough for God to send him a message that he was going to die.
King Hezekiah turned his face to the wall and prayed unto God to heal him and to give him an additional 15 years of life. God granted him his prayer request and healed him and said yes to extending his life 15 more years.
Hezekiah asked God for a 'sign'; he asked God to turn the sun dial backwards a specific measure of time. And God did just that; turned back the 'hands' of time (via the sundial).
OKAY............ NOW here's the thing about this. Hezekiah 'doubted' God's Voice. King Hezekiah was a very proud King and this interfered with his relationship with God, therefore he was in need of a 'sign'.
We have to be careful when asking God for signs, because the enemy is also very deceptive in presenting a 'sign' which may convince someone that it's a sign from God, when in reality it is not.
I am not saying that God will not and has not given people signs, because the Word of God speaks of signs and wonders... quite a few of them , in fact, many of them. However, asking for signs means that we have doubt; that there is uncertainty and this is what satan literally pounces upon.... 'our' doubt.
For example, over and over satan said unto Jesus... "Did not God say.... ? in order to tempt Jesus after he came from the wilderness and fasting for 40 days and 40 nights. satan was not only tempting Jesus (who could not be tempted), but the enemy was also trying to place doubt into the heart of Jesus. Yet.... Jesus knew His Father's voice..... His response, beyond any shadow of a doubt was... It is written....
Ending the conversation with 'Get thee behind me satan..."
God wants us to be so close to Him that we never have to doubt that He has heard our prayers; and answered them.
For as Jesus said,
'My sheep know my voice and the voice of a (the) stranger, [they] shall not follow.'
Blessings sweetheart.