Surah Fussilat 41:33

وَمَنْ أَحْسَنُ قَوْلًا مِّمَّن دَعَآ إِلَى ٱللَّهِ وَعَمِلَ صَـٰلِحًا وَقَالَ إِنَّنِى مِنَ ٱلْمُسْلِمِينَ

And who is better in speech than one who invites to Allāh and does righteousness and says, "Indeed, I am of the Muslims."

Translation: Saheeh International

Tafsir

And who speaks better words — in other words no one speaks better words — than him who summons others to God by affirming His Oneness and acts righteously and says ‘Indeed I am one of those who submit to God’?

Excerpt from Tafsir al-Jalalayn, commentary on 41:33, via Quran.com. The reader has the full commentary and 9 more tafsirs.