What did Elisha ask Elijah for before he was taken up?

Answer: A double portion of his spirit

Elijah asked what he could do for him, and Elisha asked to inherit a double portion of Elijah's spirit.

“After they had crossed over, Elijah said to Elisha, “Tell me, what can I do for you before I am taken away from you?” “Please, let me inherit a double portion of your spirit,” Elisha replied.”— 2 Kings 2:9 (BSB)