Praise be to Allah.
Seeing Allaah in this world is definitely not possible. The evidence for that is the fact that Moosa, who was one of the greatest Messengers and one of the five Messengers of strong will said: “ ‘O my Lord! Show me (Yourself), that I may look upon You’” Allaah said to him: “ ‘You cannot see Me, but look upon the mountain; if it stands still in its place then you shall see Me.’ So when his Lord appeared to the mountain, He made it collapse to dust.” So the mountain crumbled before Moosa as he was looking on, and “Moosa (Moses) fell down unconscious” So he lost consciousness, because he was watching something that he could not bear. “Then when he recovered his senses he said: ‘Glory be to You, I turn to You in repentance and I am the first of the believers.’” [Quotations from al-A’raaf 7:143 – interpretation of the meaning]. So he repented to Allaah for having asked this question, because it was asking for something that was not possible, and Allaah says (interpretation of the meaning):
“Invoke your Lord with humility and in secret. He likes not the aggressors”
Seeing Allaah in this world when one is awake is something that is not possible. Even the Prophet (peace and blessings of Allaah be upon him) on the night of the Mi’raaj (ascent into heaven) did not see his Lord. He was asked ‘Did you see your Lord?’ He said, “I saw Light.” According to another report: “Light – how could I see Him?” i.e., between me and Him there was a great veil of light. According to a hadeeth in al-Saheeh, it is narrated that Allaah is veiled in Light. That appears in the hadeeth in which the Prophet (peace and blessings of Allaah be upon him) said: “His veil is Light and if He were to remove it, the glory of His Countenance would burn everything of His creation, as far as His gaze reaches.” Because His sight reaches everything, and everything would be burned by this immense Light. Based on this, we say that it is not possible to see Allaah in this world when one is awake.
As for dreams, the Prophet (peace and blessings of Allaah be upon him) saw his Lord in a dream, but is it possible for anyone else to see Him? It is narrated that Imam Ahmad (may Allaah have mercy on him) saw his Lord, and some of the scholars said that this is possible. And Allaah knows best. But I am afraid to open the door to Sufi shaykhs and others who will start saying, “I saw my Lord last night and we chatted and talked together,” then he will come up with myths and lies for which there is no basis. I think it is better to keep this door closed from the outset.