Dictionary:

exhortation

  (ĕg'zôr-tā'shən, ĕk'sôr-)

1. The act or an instance of exhorting.
2. A speech or discourse that encourages, incites, or earnestly advises.

Definition: urging
Antonyms: discouragement

The noun has 2 meanings:

Meaning #1: a communication intended to urge or persuade the recipients to take some action

Meaning #2: the act of exhorting; an earnest attempt at persuasion
  Synonym: incitement