(Isa. 48:13; Ps. 110:1; Matt. 22:44; 25:31–46; 26:63–64; Acts 7:55)
The showing favor to the right hand or side is not something invented by man but was revealed from the heavens in the beginning… . There are numerous passages in the scriptures referring to the right hand, indicating that it is a symbol of righteousness and was used in the making of covenants… . The right hand or side is called the dexter and the left the sinister. Dexter connotes something favorable; sinister, something unfavorable or unfortunate. It is a well-established practice in the Church to partake of the sacrament with the right hand and also to anoint with the right hand, according to the custom which the scriptures indicate is, and always was, approved by divine injunction.
(Joseph Fielding Smith, Answers to Gospel Questions, 5 vols. [Salt Lake City: Deseret Book Co., 1957–1966], 1:156–58.)
Two domains of imagery emerge. The first is one of prominence or favored position. Aaron and his sons were to be sprinkled with blood on their right ear, thumb and big toe (Ex. 29:19–20; cf. Lev. 8:23–26; 14:14–28). To be seated at the right hand is to occupy a position of recognition and prestige. Solomon’s mother was given a throne at the right hand of the king (1 Kings 2:19). The messianic king is ordered to be seated at the right hand of the Lord, a position of conquest and rule (Ps. 110:1; cf. Matt. 22:44). Jesus announced his destiny to be seated at the right hand of God (Mark 14:62; Luke 22:69). Finally, to have extended the right hand was an indication of specification and favor (Gal. 2:9; Rev. 1:17)… .
The second domain of “right hand” portrays an image of intense power and strength. Most frequently it is used by the psalmists of the Lord as a God who rescues and sustains by means of his mighty “right hand” (Ps. 17:7; 18:35; 21:8; 118:15b–16; 138:7; cf. Ex. 15:6, 12)… . The conquering Jesus is portrayed as holding the seven stars in his “right hand” (Rev. 1:16; cf. 1:20; 2:1)… .
The symbolic significance of the right and left hands are evidenced in Joseph’s attempt to change his father’s deliberate crossing of his hands in the blessing of Ephraim and Manasseh (Gen. 48:13–18).
(Dictionary of Biblical Imagery, ed. Leland Ryken, James C. Wilhoit, and Tremper Longman III [Downers Grove, Illinois: InterVarsity Press, 1998], 361.)