2 Chronicles 11:14
For the Levites left their suburbs and their possession, and came to Judah and Jerusalem: for Jeroboam and his sons had cast them off from executing the priest’s office unto the LORD: For the Levites left their suburbs and their possession, and came to Judah and Jerusalem: for Jeroboam and his sons had cast them off from executing the priest’s office unto the LORD:
Jeroboam and his sons cast off the Levites from executing the priest's office to the Lord, excluding them from serving as priests to Him. Their rejection of the Levites' priestly service drove many faithful Levites from their homes. The Levites therefore left their towns and their possessions and came to Judah and to Jerusalem. They made this move so that they could worship the Lord according to His requirements.
Their departure was part of a wider movement of God-fearing people from the northern tribes who came to Jerusalem to worship the Lord. This influx of faithful worshipers strengthened Judah during the early years of Rehoboam's reign.