وَلَقَدْ حَفِظْتُ وَصَاةَ عَمِّي بِالضُّحَى إِذْ تَقْلِصُ الشَّفَتَانِ عَنْ وَضَحِ الْفَمِ
I kept my uncle’s charge in the bright forenoon, in an intense moment when lips drew back and teeth showed.
Waṣāt ʿammī is an uncle’s charge or counsel. Taqliṣu al-shafatān depicts lips withdrawing to expose the teeth, a concrete image of strain. The temporal particle idh locates the moment when the poet claims to have honoured the charge.