What is the meaning of the Almighty’s saying: "until it returned like the old date-stalk"?

The meaning of "like the old date-stalk" is that when the moon becomes fine, curved, and narrow in its last phases, it resembles the dry, bent date-stalk that remains on the palm tree after the spathes have been cut. The moon is likened to it in three aspects: fineness, curvature, and yellowness. The term "old" is applied to something that has passed a year or more.