Commentary for Isaiah 1:30

whose leaves wilt Its leaf ([Other editions read:] whose leaf) wilts, becomes wilted [flatisant in O. F.]. When heat or cold comes upon it, it wilts and its moisture is lost and destroyed. [The word] נבל is not an expression of decay like בלה, for no ‘nun’ is found in that expression, but נבל [is an expression of something that becomes fatigued and its strength is curtailed, from the root of] נָבֹל תִּבֹּל (Exod. 18: 18), which Onkelos renders: You will surely be exhausted.

For he shall be as an oak tree, etc. After having said that they shall be ashamed of the oak trees they have coveted and stolen, the prophet compares them to an oak tree whose leaves have withered.

that has no water to water its seeds; to the thing with which they sin, he compares their punishment.