Contradiction with 1 Chronicles 23:13
This verse mentions the duties specific to the sons of Aaron, which could suggest a contradiction if 1 Chronicles 23:18 implies different duties or roles for the Levites than elsewhere mentioned.
1 Chronicles 23:13: The sons of Amram; Aaron and Moses: and Aaron was separated, that he should sanctify the most holy things, he and his sons for ever, to burn incense before the LORD, to minister unto him, and to bless in his name for ever.
Contradiction with Numbers 3:9
This verse says that the Levites are wholly given to Aaron and his sons, which might contradict any implication in 1 Chronicles 23:18 of an independent role for the Levites.
Numbers 3:9: And thou shalt give the Levites unto Aaron and to his sons: they [are] wholly given unto him out of the children of Israel.
Contradiction with Deuteronomy 18:1-2
This verse states that the Levites have no inheritance among their brethren, which may contradict with 1 Chronicles 23:18 if it suggests otherwise regarding their inheritance or roles.
Deuteronomy 18:1-2: The priests the Levites, [and] all the tribe of Levi, shall have no part nor inheritance with Israel: they shall eat the offerings of the LORD made by fire, and his inheritance.
Contradiction with Hebrews 7:11-12
This verse speaks about the change in priesthood, which might seem contradictory if 1 Chronicles 23:18 implies permanence of the Levitical order and duties.
Hebrews 7:11-12: If therefore perfection were by the Levitical priesthood, (for under it the people received the law,) what further need [was there] that another priest should rise after the order of Melchisedec, and not be called after the order of Aaron?
Contradiction with Numbers 8:24
This verse specifies the age and time of service for the Levites, which might contradict details in 1 Chronicles 23:18 if their service duration is depicted differently.
Numbers 8:24: This [is it] that [belongeth] unto the Levites: from twenty and five years old and upward they shall go in to wait upon the service of the tabernacle of the congregation: [to...: Heb. to war the warfare of, etc]