The Table Spread - 5:115
"Allah said: "I will send it down to you,"He said: "Whoever disbelieves after that, I will punish him with a torment which I have never given to anyone."
Allah displays miracles for those who believe:
The Cow/2:260
"Abraham said, "My Lord, show me how You raise the dead."He said, "Or do you not believe?"He said, "Yes, but to strengthen my heart.""Take four birds and examine them thoroughly (recognize their different characteristics). Then place a piece of them on each mountain. Then call them. They will come to you immediately. Know that Allah is Mighty, Wise."
The Heights/7:143
"When Moses came to us at the appointed time and his Lord spoke to him, he said, "My Lord, appear to me and let me look at you. "You cannot see me. But look at this mountain; if it stands still, then you will see me."When his Lord appeared to the mountain, He shattered it, and Moses fell unconscious. When he came to his senses, he said, "You are great, to You I turn, and I am the foremost of the believers."
The Cow/2:118
"The ignorant said, "Should not Allah have spoken to us or a sign (miracle) have come to us?"Those before them had spoken like them. Their minds are alike. We show the miracles to those who believe."
The Cattle/6:111
And if We send down to them angels, and the dead speak to them, and We bring everything before them, they will not believe, except those whom Allah wills. But most of them do not know this truth.