يَسْأَلُونَكَ عَنِ الْأَهِلَّةِ قُلْ هِيَ مَوَاقِيتُ لِلنَّاسِ وَالْحَجِّ
They ask you about the crescent moons. Say: they mark times for people and the pilgrimage. (Al-Baqarah 2:189)
Rather than dwelling on the visible waxing and waning alone, the response identifies its practical significance for timekeeping and pilgrimage.
Uslub al-hakim is not simply answering an unrelated question. It shifts from an immediately noticed feature to the more useful dimension of the same subject.