No one has seen God and lived. To see God we must be non-existent.
Commentary by Hazrat Inayat Khan:

There is a [Hadith] which says: Mutu kubla anta mutu, which means, 'Die before death.' A poet says, 'Only he attains to the peace of the Lord who loses himself.' God said to Moses, 'No man shall see me and live.' To see God we must be non-existent.
What does all this mean? It means that when we see our being with open eyes, we see that there are two aspects to our being: the false and the true. The false life is that of the body and mind, which only exists as long as the life is within. In the absence of that life the body cannot go on. We mistake the true life for the false, and the false for the true.
As life unfolds itself to man the first lesson it teaches is humility; the first thing that comes to man's vision is his own limitedness. The vaster God appears to him, the smaller he finds himself. This goes on and on until the moment comes when he loses himself in the vision of God. In terms of the Sufis this is called fana, and it is this process that was taught by Christ under the name of self-denial. Often man interprets this teaching wrongly and considers renunciation as self-denial. He thinks that the teaching is to renounce all that is in the world. But although that is a way and an important step which leads to true self-denial, the self-denial meant is the losing oneself in God.

The first lesson of the mystic is, "Thou art, and not I." It is not only complete surrender to God, it is self-effacement. And what does the symbol of the cross explain? That "Thou art, not me, my hands are not for me, my feet are not for me, my head is not for me, they are all Thine." The saying of the [Hadith], "Die before death," does not mean suicide, it means the death of the "I", the separate self.