«فَنَهَضْتُ حِينَ سَجَا الدُّجَى عَلَى مَا بِي مِنَ الْوَجَى»
I rose when the darkness had settled, despite the pain in my feet.
Sajā conveys stillness; dujā is the darkness of night; wajā is soreness, especially in the feet after travel. Dujā / wajā rhyme without having the same meaning.
The contrast between a still night and the traveller’s aching movement makes his need urgent. He cannot remain at rest merely because the surroundings are quiet.