لِسَانُ الْفَتَى نِصْفٌ وَنِصْفٌ فُؤَادُهُ ۞ فَلَمْ يَبْقَ إِلَّا صُورَةُ اللَّحْمِ وَالدَّمِ
Half a person’s worth lies in his tongue and half in his heart and understanding; what remains is only the physical form of flesh and blood.
Lisān represents expressive ability, and fuʾād the heart, intention, discernment and inward understanding. The two halves are a rhetorical division of human worth, not a biological claim. The “form of flesh and blood” contrasts mere bodily appearance with qualities demonstrated in thought and language.