What is the significance of Yonah's concern for the Kikayon?
Radak: He was concerned for it only due to his pain. So Hashem is concerned for Ninveh for His honor, for the creations are His honor - "Melo Chol ha'Aretz Kevodo" (Yeshayah 6:3). All the more so His honor is from man - "v'Lichvodi Berasiv" (ibid. 43:7). Even though I explained that this refers to Yisrael, in any case it refers to people - "Yetzartiv Af Asisiv" (ibid.) However, since Yisrael recognize Kevod Hashem more than other people, except for the Chachamim among the nations, the verse discusses Yisrael.
Malbim: Chas is compassion because he needs the matter, e.g. "v'Einechem Al Tachos Al Keleichem" (Bereishis 45:20). You were Chas for the Kikayon because you needed it for shade, even though other than this, nothing would sadden you about its loss. You did not toil for it; refer to 4:10:3:2.
What toil did he not do for it?
Rashi: He did not plow, seed and water it.
Malbim: He did not plant it and raise it.
Why is it relevant that he did not toil for it?
Radak: One who toils for something, he is sadder when it is lost. Even though Hashem did not toil to form the creations, Dibrah Torah k'Leshon Bnei Adam (the Torah anthropomorphizes, to help people understand).
Malbim: Normally a worker is Chas for what he made, not due to the matter, that it is dear and lasting. The Kikayon sprouted in one night, and perished in one night - it was like a flower that falls, without real import.
What is the meaning of "she'Bin Laylah"?
Rashi: This is like Ben Laylah - it grew in only one night. Radak - also [Yehoshua] bin Nun is like Ben Nun. It sprouted in one night, and perished at the end of the next night - at dawn it was stricken and dried.
