Jesus asked the question of the blind man “What do you want Me to do for you?” Luke 18:41

It begs to question why Jesus would ask such an obvious question of the blind man. Jesus knew he was blind. 
God wants us to declare with our mouth what we desire, so all can testify to the answered request.

“And whatever you ask in My name, that I will do, that the Father may be glorified in the Son.” John 14:13 

“Then Jesus said to him, “Receive your sight; your faith has made you well.” And immediately he received his sight, and followed Him, glorifying God. And all the people, when they saw it, gave praise to God.” Luke 18:42-43 ‭NKJV‬‬