1. Zadok: The Faithful Priest
And I will raise me up a faithful priest, that shall do according to that which is in mine heart and in my mind: and I will build him a sure house; and he shall walk before mine anointed for ever. (1Sa 2:35)

2. Genealogy of Aaron (Abridged)
1Ch 6:3
Eleazar
Zerahiah
1Ch 6:6
Meriaoth
Amariah
1Ch 6:7
Ahitub
Zadok
1Ch 6:8
Ithamar
Eli
1Sa 1:9
Hophni
1Sa 1:3
Phineas
1Sa 14:3
Ahiah
Abimelech
1Sa 22:9
Abiathar
1Sa 22:20; 1Ch 24:3
Ichabod
1Sa 4:21

3. A Tale of Two Priests Numbers 25 & 1 Samuel 2
Why was God angry?
Israel joined themselves with Baal Peor, committing idolatry and sexual immorality (Num 25:3)
Eli’s sons, Hophni & Phineas, took the best of the sacrifices meant for God for themselves (1Sa 2:15-17)
How was God’s tabernacle defiled?
Zimri, a Simeonite, laid with a Midianitish woman in front of those gathered at the door of the tabernacle (Num 25:6)
Eli’s sons laid with the women that assembled at the door of the tabernacle (1Sa 2:22)
How did the priest react?
Phineas rose up and took action against those that angered God (Num 25:7-8)
Eli sat at the door of the temple, took no effective action against his sons (1Sa 1:9; 2:23-25)
What was God’s estimation of this priest?
Phineas was zealous on God’s behalf (Num 25:11)
Eli loved his sons more than he loved God, and he scorned the things God desired (1Sa 2:29)
How did God reward the priest for their action?
A covenant of peace, an everlasting priesthood, and righteousness imputed to him forevermore (Num 25:12-13; Psa 106:30-31)
Descendants will die by the sword, the priesthood removed, considered guilty for his apathy. (1Sa 2:31-33; Exo 34:7)

4. Genealogy of Aaron (Abridged)
1Ch 6:3
Eleazar
Zerahiah
1Ch 6:6
Meriaoth
Amariah
1Ch 6:7
Ahitub
Zadok
1Ch 6:8
Ithamar
Eli
1Sa 1:9
Hophni
1Sa 1:3
Phineas
1Sa 14:3
Ahiah
Abimelech
1Sa 22:9
Abiathar
1Sa 22:20; 1Ch 24:3
Ichabod
1Sa 4:21