The Rabbi of Gastinin, of blessed memory, made it a practice never to express anger on the same day when he was upset or annoyed with someone. Only on the following day would he tell him, "Yesterday I was annoyed at you." (Siah Sarfei Kodesh, III, p. 29, #37)

There are many variations on this tactic of delay, so that an unjust anger dissipates completely, or so that a just anger can be purified of alien fire (such as pride).

Yitzhak Buxbaum in Jewish Spiritual Practices