Al-Ahzab 33:32

Ya nisaa annabiyyilastunna kaahadin mina annisa-i iniittaqaytunna fala takhdaAAna bilqawli fayatmaAAaallathee fee qalbihi maradun waqulna qawlanmaAAroofa

O wives of the Prophet, you are not like anyone among women. If you fear Allāh, then do not be soft in speech [to men], lest he in whose heart is disease should covet, but speak with appropriate speech.

O wives of the prophet, you are not like any other women, if you observe taqwā (righteousness). So, do not be too soft in your speech, lest someone having disease in his heart should develop fancies (about you); and do speak with appropriate words.