The Prophet (peace and blessings of Allah be upon him) saw Paradise
Question

I want to know if Prophet mohammed has seen the heaven?
Praise be to Allah.Many texts indicate that Paradise and Hell are two creations which currently exist, and that the Prophet (peace and blessings of Allah be upon him) saw Paradise and Hell. This is proven by many events, for example: 
The hadeeth of ‘Abd-Allah ibn ‘Abbaas, who said: “There was an eclipse of the sun during the time of the Messenger of Allah (peace and blessings of Allah be upon him), and the Messenger of Allah (peace and blessings of Allah be upon him) prayed… Then he said, ‘The sun and the moon are two of the signs of Allah. They do not become eclipsed because of the death of somebody or because of his life (i.e. birth). So when you see them, remember Allah.’ The people said, O Messenger of Allah, we saw you taking something from where you were standing, and then we saw you retreating.’ The Prophet (peace and blessings of Allah be upon him) replied, ‘I saw Paradise and stretched my hands towards a bunch (of its fruits) and had I taken it, you would have eaten from it as long as the world remains. I also saw the Hell-fire and I had never seen such a horrible sight. I saw that most of its inhabitants were women.’ The people asked, ‘O Messenger of Allah, why is that?’ The Prophet (peace and blessings of Allah be upon him) replied, ‘Because of their ungratefulness.’ It was asked, ‘Are they ungrateful to Allah?’ The Prophet (peace and blessings of Allah be upon him) said, ‘They are ungrateful to their life companions (husbands) and ungrateful for good deeds. If you are kind towards one of them throughout life, then she sees anything (undesirable) in you, she will say, “I have never seen anything good from you.”’”
(This version narrated by al-Bukhaari, 1052; also narrated by Muslim, 901) 
And the Prophet (peace and blessings of Allah be upon him) saw Paradise in his dreams, and the dreams of the Prophets are a form of wahy (revelation) and are true; he saw al-Rumaysa’ in Paradise; he saw a palace belonging to ‘Umar ibn al-Khattaab in Paradise; and he saw Paradise on the night of the Mi’raaj when the Sidrah (lote-tree of the utmost boundary) was covered with what it was covered with. And Allah knows best.