For the overseer must be above reproach as God’s steward, not self-willed, not quick-tempered, not addicted to wine, not pugnacious, not fond of sordid gain,…
Titus 1:7 (emphasis mine)

Elders must not be easily angered. They will be dealing with some of the most challenging and heart-breaking situations. They will have to oppose those who are living contrary to the instructions in God’s word. They will have to navigate difficult decisions that will seriously impact the life of the church. In the midst of all of these situations, they must not be given to anger.

The book of Proverbs reminds us of the dangers associated with being quick-tempered:

A quick-tempered man acts foolishly, and a man of evil devices is hated.
Proverbs 14:17

A hot-tempered man stirs up strife, but the slow to anger calms a dispute.
Proverbs 15:18

An angry man stirs up strife, and a hot-tempered man abounds in transgression.
Proverbs 29:22

The one who is quick-tempered will act foolishly and will stir up strife. Leaders must not contribute to the problems in the church; they are to be examples to the flock. The book of Proverbs commends the man who is slow to anger. He will be able to calm a dispute and will be better than the mighty.

He who is slow to anger is better than the mighty, and he who rules his spirit, than he who captures a city.
Proverbs 16:32

Additionally, Paul teaches us that we are to be imitators of God (Eph. 5:1). One of the defining characteristics of God is the fact that He is slow to anger.

The LORD is compassionate and gracious, slow to anger and abounding in lovingkindness.
Psalm 103:8