be at ease

See: rest
References in classic literature ?
This influence of habit was necessarily strong in a man whose life was so monotonous as Marner's-- who saw no new people and heard of no new events to keep alive in him the idea of the unexpected and the changeful; and it explains simply enough, why his mind could be at ease, though he had left his house and his treasure more defenceless than usual.
And how could he be at ease with his conscience because "as always, in the current case I performed my duty towards my country as an honourable citizen with integrity"?