נֹתֵ֥ן לַיָּעֵ֖ף כֹּ֑חַ וּלְאֵ֥ין אוֹנִ֖ים עָצְמָ֥ה יַרְבֶּֽה׃
疲乏的，他賜予力量；軟弱無力的，他加添氣力。
Tze'enah Ure'enah
“He gives strength to the weary” [40:29]. When the Holy One wants to, He gives strength to Israel who are in exile to endure the difficult exile and, He strengthens those who are not strong.3Radak, Isaiah, 40:29.
Rashi
Who gives the tired strength And who will eventually renew strength for your tiredness.
Ibn Ezra
He giveth power, etc. How can He be weary, if He gives power to the faint, and strengthens him that is without strength. עָצְמָה Strength. It is a noun similar in form to חָבְמָה wisdom.