Wonderfully, God revealed the dream to Daniel. Daniel knew this with the certainty that comes with every communication from God, and which the prophets also experienced the word they received from the Lord.
That is a thing that is true with us, when we are carried away and uplifted by God's plan for the world, and for the ages, and for the future generations according to these great themes. We forget all about our aches and pains, and problems and needs, which perhaps we started to bring to the Lord in prayer. That is exactly what happens here; there is no further mention of the safety of Daniel.