וַיֹּ֖אמֶר הִקְשִׁ֣יתָ לִשְׁא֑וֹל אִם־תִּרְאֶ֨ה אֹתִ֜י לֻקָּ֤ח מֵֽאִתָּךְ֙ יְהִֽי־לְךָ֣ כֵ֔ן וְאִם־אַ֖יִן לֹ֥א יִהְיֶֽה׃
Odpowiedział tedy: Trudnej rzeczy zażądałeś. Jeśli mnie zobaczysz, gdy zabiorą mnie od ciebie, tedy się to ziści tobie, a jeśli nie, nie ziści się tobie.
Rashi
You have made a difficult request. It is impossible [for me] to give you more than I possess.5According to Rashi, Elisha apparently asked for a double portion of Eliyahu’s spirit. Alternatively, Elisha requested to attain two thirds of Eliyahu’s spirit and for all other prophets together to attain one third. -Radak Or, Elisha requested double the spirit of any other prophet.—Ralbag
Radak
You asked something difficult ~ It would have been enough for you if you had asked a just part of my spirit, or even half, but asking for it twice is something difficult, and even though [it is difficult] if you have the spiritual strength to see me as I am taken from you then I will know that from God this will happen, and so you will have what you asked.
Rashi
If you will witness my departure from you. Then I will be able to do more and more.6I.e., if you are spiritually elevated enough to observe my ascent, it would be an indication that your request would be granted.
Rashi
It will be so for you, and if not, it will not be. That I am unable [to do so].