Speak not evil one of another, brethren.
— Jas 4:11 WEB
Let all bitterness, and wrath, and anger, and clamor, and evil speaking, be put away from you, with all malice.
— Eph 4:31 WEB
If aught good thou canst not say
Of thy brother, foe, or friend,
Take thou, then, the silent way,
Lest in word thou shouldst offend.
If there is any person to whom you feel dislike, that is the person of whom you ought never to speak.
To recognize with delight all high and generous and beautiful actions; to find a joy even in seeing the good qualities of your bitterest opponents, and to admire those qualities even in those with whom you have least sympathy, this is the only spirit which can heal the love of slander and of calumny.
—F. W. ROBERTSON