What Ketz does he want to know?
Rashi: How long will be our affliction?
Radak: This is like Iyov said "u'Mah Kitzi Ki A'arich" (Iyov 6:11). If my end (lifetime) will be according to the usual lifespan, I will bear it until You heal me, and after I will be healthy. However, if my end is short, I should die soon from my illness, for I cannot bear this great pain without hope after it in this world.
Malbim: Man resides in two worlds. If he looks down at his body, he resides in this lowly physical world. If he looks above at his Nefesh, he is one of Bnei Elokim, free to act according to choice. His powers are unlimited. These two roots in man are constantly at war. Natural laws oppose choice. Inform me in which world I am - what is the essence of these two roots? Kitzi is the spiritual root, the Ketz (end) of man. Midas Yamai is temporary life, which has a measure and end.
What is the meaning of "Meh Chadal Ani"?
Radak: Chadal is a To'ar (adjective). The noun is "Im Yoshvei Chadel" (Yeshayah 38:11, i.e. the world; it is the same as Cheled, just the letters are reversed). I.e. how long will I be in this world?
Malbim: From which world am I?
