The Letter Sad 38:20. Juz 23, page 454.
وَشَدَدْنَا مُلْكَهُۥ وَءَاتَيْنَـٰهُ ٱلْحِكْمَةَ وَفَصْلَ ٱلْخِطَابِ٢٠
We made his kingdom strong and gave him wisdom and decisive speech.
Sad 38:20, translated by Marmaduke Pickthall