Clean Hands and a Pure Heart

John A. Tvedtnes in Temple Prayer in Ancient Times explains how:

There is symbolism in raising the hands in prayer. The gesture exposes to God both the breast and the palms of the petitioner to show that they are pure (clean). This is reflected in one of the temple hymns found in the Bible, Psalm 24, which Donald W. Parry has suggested may relate to a prayer circle: (Donald W. Parry, "Temple Worship and a Possible Reference to a Prayer Circle in Psalm 24," BYU Studies 32/4 (1992): 57—62.)

Who shall ascend into the hill of the Lord? or who shall stand in his holy place? He that hath clean hands, and a pure heart; who hath not lifted up his soul unto vanity, nor sworn deceitfully. (Psalm 24:3—4)

The message of the Psalm is clear: In order to enter into the temple (the "hill of the Lord," called "the mountain of the Lord's house" in Isaiah 2:2), one must have clean hands and a pure heart. (Compare Doctrine and Covenants 88:74: "purify your hearts, and cleanse your hands and your feet before me, that I may make you clean." Doctrine and Covenants 88 contains many temple elements. Also note one of Jesus' beatitudes, "Blessed are the pure in heart: for they shall see God" (Matthew 5:8), which reminds us that, in ancient Israel, God frequently appeared to the prophets in his temple. Returning to Psalm 24, we note that verse 6 speaks of those who seek the face of the Lord.)

In other words, both acts (represented by the hands) and thoughts (represented by the heart) must reflect righteousness, along with the lips that utter the prayer.(The Book of Mormon teaches that God will judge us on the basis of our actions, our words, and our thoughts (see Mosiah 4:30; Alma 12:14; compare D&C 18:38; D&C 88:109; D&C 137:8-9; Isaiah 55:7; Matthew 12:36—37; Matthew 15:19; Mark 7:21; Acts 8:22). According to 2 Enoch (J) 71:10, one can sin before God by word and thought, while in 3 Enoch 45:1, we read that the deeds and thoughts of all mankind are written on the curtain that hangs before God. The Testaments of the Twelve Patriarchs indicate that we should love in deeds and thoughts, in the heart (see Testament of Gad 6:1, 3; 7:7; compare Testament of Joseph 4:6).)

This is probably what the author of Job had in mind when he wrote, "prepare thine heart, and stretch out thine hands toward him" (Job 11:13). Note also Lamentations 3:41, "Let us lift up our heart with our hands unto God in the heavens."