Surah Fussilat — Ayah 33 (41:33)
وَمَنۡ أَحۡسَنُ قَوۡلٗا مِّمَّن دَعَآ إِلَى ٱللَّهِ وَعَمِلَ صَٰلِحٗا وَقَالَ إِنَّنِي مِنَ ٱلۡمُسۡلِمِينَ ٣٣
English translation (Saheeh International)
And who is better in speech than one who invites to Allāh and does righteousness and says, "Indeed, I am of the Muslims."
Brief commentary
There is no one whose speech is better than the one who calls towards the oneness of Allah and acting upon His law, whilst doing good actions that please Him, saying, “Indeed, I am one of those who submit and humble myself to Allah”. Indeed, whoever does all that is the one who is best in speech.