'Severity' in the Bible

he will treat him with the utmost severity and assign him a place among the hypocrites: there will be the weeping and the gnashing of teeth.

Notice therefore God's kindness and God's severity. On those who have fallen His severity has descended, but upon you His kindness has come, provided that you do not cease to respond to that kindness. Otherwise you will be cut off also.

These rules have indeed an appearance of wisdom where self-imposed worship exists, and an affectation of humility and an ascetic severity. But not one of them is of any value in combating the indulgence of our lower natures.