sureness

The state of being sure; certainty.

For more sureness he repeats it.

The law holds with equal sureness for all right action.

noun

1. The fact or condition of being without doubt: assurance, assuredness, certainty, certitude, confidence, conviction, positiveness, surety. See certain/uncertain.
2. Reliability in withstanding pressure, force, or stress: fastness, firmness, hardness, security, soundness, stability, stableness, steadiness, strength, sturdiness. See better/worse, change/persist, continue/stop/pause.

The noun has 2 meanings:

Meaning #1: freedom from doubt; belief in yourself and your abilities
  Synonyms: assurance, self-assurance, confidence, self-confidence, authority

Meaning #2: the quality of being steady and unfailing