A common misinterpretation of this verse treats it as a universal personal promise for believers to gain physical or material strength and success in any endeavor, akin to a prosperity gospel assurance, overlooking its specific historical and covenantal context as God's oracle to David alone; others might spiritualize it exclusively as fulfilled only in Christ without acknowledging the initial Davidic application, or misconstrue 'hand' and 'arm' as mere human effort empowered by God rather than God's own omnipotent intervention upholding the monarchy.
Psalms 89:21
King James Version (1769)
21 With whom my hand shall be established: mine arm also shall strengthen him.
Psalms 89:21 expresses God's solemn promise within the Davidic covenant to empower and sustain His anointed king by establishing His own hand upon him and strengthening him with divine arm, symbolizing unwavering divine power, protection, and faithfulness that ensures the king's throne endures victoriously against enemies, reflecting God's sovereign choice and eternal commitment to David's lineage as a testimony to His covenant-keeping nature.