שמואל ב, פרק י״ט, פסוק ל״ה

An invitation to join the royal court is met with a profound acceptance of old age and a realistic view of human limitations. In responding to King David, Barzillai questions his remaining years, posing a rhetorical question about how much time he actually has left to live [מצודת ציון, רש"י, מצודת דוד]. The prospect of traveling with the king means making the journey to Jerusalem [ביאור שטיינזלץ]. The primary approach among commentators is that his extreme age makes such a move entirely unjustified; because his days are numbered, the sheer effort of uprooting his life makes no sense [מלבי"ם].

Furthermore, relocating to the capital would be pointless for both men. From Barzillai's perspective, his frail physical condition leaves him unable to enjoy the king's provisions or the luxuries of palace life [רש"י, מצודת דוד, אברבנאל]. From King David's perspective, if the invitation was intended to secure Barzillai as an advisor, his advanced age has dulled his ability to distinguish good from bad, rendering his counsel useless [אברבנאל].

Beyond being impractical, the journey poses a genuine physical danger. The travel would be so exhausting for a man of his age that he could easily die before even reaching Jerusalem. In this way, the favor the king wishes to grant him would actually become a tragedy [אברבנאל]. Providing deeper context for his severe physical decline, ancient sages note that old age overtook Barzillai with unusual speed because he had been deeply involved in immoral behavior [אברבנאל].