1)
Why will Elisha be Navi in place of Eliyahu?
1.
Rashi (from Mechilta Bo 12:1): I do not desire your Nevu'ah, for you prosecute against My children.
2.
Radak: Since you want to leave the world, you must leave a Navi in place of you.
3.
Malbim: Refer to 19:14:1:1.
