When He made the world, He made two ways to repair each thing: With harshness or with compassion. With a slap or with a caress. With darkness or with light.
“And G‑d looked at the light and saw that it was good.” Darkness and harsh words may be necessary. But He never called them good.
Even if you could correct another person with harsh words, the One Above receives no pleasure from it. When He sees his creatures heal one another with caring and with kindness, that is when He shines His smile upon us.
—cited from Kedushas Levi on Shabbos Vayechi, 5751.