“Take the Levites from among the children of Israel, and purify them” (Numbers 8:6). “Take the Levites” – Halakha, how many strings were on the lute that the Levites would play? Rabbi Yehuda said: There were seven strings on the lute, as it is stated: “Abundant [sova] joy in Your presence, [eternal] pleasure” (Psalms 16:11). Do not read it as abundant, but rather as seven [sheva] joys.
Likewise, David said: “Seven times a day do I praise You for Your righteous ordinances” (Psalms 119:164). But in the messianic era it will become eight, as David said regarding the melody: “For the conductor: With instrumental music on the eight-stringed lute” (Psalms 6:1). And in the future it will become ten, as it is stated: “God, I will sing a new song to You on a ten-stringed harp” (Psalms 144:9).
Who instituted it for them? It was Samuel and David, as it is stated: “It was they who were established, by David and Samuel the seer, in their entrusted task [be’emunatam]” (I Chronicles 9:22).6It is expounded as though it were beomanutam, their music. And they established the divisions for song. The Levites would stand on the platform and sing before the One who spoke and the world came into being.
See the love that the Holy One blessed be He loved the Levites. So said the Holy One blessed be He to Moses: ‘The Levites are greatly beloved before Me. Take them for a position of authority in My name.’ From where is it derived? It is from what we read regarding that matter: “Take the Levites.”