Him I call indeed a Brâhmana who utters true speech, instructive and free from harshness, so that he offend no one.
Akakkasaṁ viññāpaniṁ, giraṁ saccamudīraye; Yāya nābhisaje kañci, tamahaṁ brūmi brāhmaṇaṁ.
Dhammapada 408
The same idea in other traditions
Keep thy tongue from evil, And thy lips from speaking guile.
A soft answer turneth away wrath: but grievous words stir up anger.
Truth is higher than everything; but higher still is truthful living.
O ye who believe! Fear Allah, and (always) say a word directed to the Right:
The Master said, "The superior man wishes to be slow in his speech and earnest in his conduct."
By simplicity he will become upright in actions, thoughts, and speech, and he will become veracious; thereby he will truly practise the Law.
Be silent, O thou who knowest many things! for he that speaketh little will be free from reproach on the Day of Judgment. The man of many words is deaf; no counsel does he heed like silence. …
The true prevails, not the untrue; by the true the path is laid out, the way of the gods (devayânah), on which the old sages, satisfied in their desires, proceed to where there is that highest place of the True One.