A reason given for choosing your words
The verse explains what happens if you do not.
وَقُل لِّعِبَادِى يَقُولُوا۟ ٱلَّتِى هِىَ أَحْسَنُ ۚ إِنَّ ٱلشَّيْطَـٰنَ يَنزَغُ بَيْنَهُمْ ۚ إِنَّ ٱلشَّيْطَـٰنَ كَانَ لِلْإِنسَـٰنِ عَدُوًّا مُّبِينًا
Wa qul li-ʿibādī yaqūlu-llatī hiya aḥsan, inna-sh-shayṭāna yanzaghu baynahum…
“And tell My servants to say that which is best. Indeed, Satan induces [dissension] among them. Indeed Satan is ever, to mankind, a clear enemy.”
Source
The Qur'an · 17:53
Qur'an
- Qur'anic text in the Uthmani script via Quran.com; translation: Saheeh International