الْكَرَمُ تَحْتَ رِدَائِهِ
Generosity lies under his cloak; the wearer himself is generous.
Al-karam explicitly names the quality; «تحت ردائه» places it beneath the garment. The garment is not treated as a literal physical storehouse of generosity. The communicative result is the quality’s attribution to the wearer.
The quality is already named; the indirection concerns who possesses it. This makes the expression kinayah of attribution.