From
李商隐《
晚晴》 (Li Shangyin, late Tang):
天意怜幽草,
人间重晚晴 (Heaven's will pities the hidden grass; the human world treasures the clear evening sky). Originally about valuing fine weather after a rain near life's end; became the canonical metaphor for respecting elders and cherishing one's later years. Confirmed in
新华成语词典 as an established set phrase.