أَشِدَّاءُ عَلَى الْكُفَّارِ رُحَمَاءُ بَيْنَهُمْ
They are stern toward the disbelievers and merciful among themselves.
The semantic contrast between sternness and mercy must be read with the different recipients and occasions in view. It is not an assertion of an unqualified contradiction in character; each quality is appropriate to its own object. A good answer therefore explains context as well as identifying contrasting meanings.
Antithesis (ṭibāq) can consist in a single opposed pair. More elaborate correspondence (muqābalah) sets out a sequence of related meanings and then their opposites in a corresponding order. Every pair of contrasts does not by itself establish the full structure of muqābalah.