2 Kings 2:9-10

And when they were gone over, Elias said to Eliseus: Ask what thou wilt have me to do for thee, before I be taken away from thee. And Eliseus said: I beseech thee, that in me may be thy double spirit.

And he answered: Thou hast asked a hard thing; nevertheless, if thou see me when I am taken from thee, thou shalt have what thou hast asked: but if thou see me not, thou shalt not have it.