بِأَنَّا الْمُطْعِمُونَ إِذَا قَدَرْنَا وَأَنَّا الْمُهْلِكُونَ إِذَا ابْتُلِينَا
That when we have the means we feed others, and when we are tested we prove destructive to our opponents.
Al-muṭʿimūn is a plural active participle, “those who feed”; al-muhlikūn means “those who destroy.” The juxtaposition moves from generosity to the claimed ability to overpower enemies.
The two idhā clauses present different circumstances: possession of resources and exposure to a test. Their syntactic symmetry constructs a boast of hospitality in ordinary times and resolve during conflict.