In the eighth month of the second year of Darius, the word of the LORD came to the prophet Zechariah son of Berekiah, the son of Iddo...   Zechariah 1:1 (NIV)

The opening of this Old Testament book identifies the time "the word of the LORD came to the prophet Zechariah." Compared to the introduction of Haggai, it is apparent that these two prophets were contemporaries.
In the second year of King Darius, on the first day of the sixth month, the word of the LORD came through the prophet Haggai...   Haggai 1:1a (NIV)
But even if they knew each other and shared the word of the LORD that came to them, they had different messages:
- Haggai preached about restoring the house of God

- Zechariah preached about restoring the holiness of God's people
Each man had received a specific word from the LORD, a unique ministry.

And so it is with all those who proclaim the word of the LORD.

Yes, I must know and declare "
the whole counsel of God" (Acts 20:27 NKJV) as revealed in Scripture, and show myself "as one approved, a workman who does not need to be ashamed and who correctly handles the word of truth" (2 Timothy 2:15b NIV).

But the Spirit of God has personally instructed me and prepared me for ministry. Though the Word stands eternal and unchanged by human interpretation (or misinterpretation), yet I have a singular life message for which the LORD has shaped me from before the foundation of the world.

I must not, therefore, covet the ministry of another of His servants.
For when one says, "I follow Paul," and another, "I follow Apollos," are you not mere men?

What, after all, is Apollos? And what is Paul? Only servants, through whom you came to believeâ€"as the Lord has assigned to each his task. I planted the seed, Apollos watered it, but God made it grow. So neither he who plants nor he who waters is anything, but only God, who makes things grow. The man who plants and the man who waters have one purpose, and each will be rewarded according to his own labor. For we are God's fellow workers; you are God's field, God's building.

1 Corinthians 3:4-9 (NIV)

Amen. Come, Lord Jesus.